12.4

LOSS OF VISUAL REFERENCE DURING LANDING

To initiate a wave-off following loss of visual reference during landing; proceed as follows.

*1.  Collective--Increase to climb.

WARNING

                •Not only must descent be stopped to prevent impact with the surface; but also a positive rapid climb is necessary to regain visual flight conditions.  Any delay may allow drift to develop; which could cause impact with ground/obstacles.

                •Consideration should be given to external cargo jettison.

*2.  Cyclic--Hover attitude (on instruments).

*3.  Selected heading--Maintain.

12.5

EXTERNAL CARGO JETTISON

*1.  Area — Clear if possible.

*2.  Cargo release — Activated.

WARNING

Prior to jettison of external cargo; alert the crew to prevent injury.

12.6

TWO-POINT CARGO SUSPENSION SYSTEM HOOK OPEN ADVISORY LIGHTS

FWD or AFT HOOK OPEN advisory lights indicate the respective hook latch mechanism is not fully overcenter and the load is susceptible to inadvertent release.  If the FWD HOOK OPEN or AFT HOOK OPEN advisory lights illuminate while carrying an external load; proceed as follows:

1.  Avoid abrupt control movements and attitude changes.

2.  Land as soon as practical.

WARNING

Do not attempt to move hook linkage or troubleshoot the systems until the load is safely on deck.

12.7

SINGLE- OR DUAL-ENGINE LANDING

Safe emergency single or dual-engine landings can be made provided they are initiated within reasonable airspeed and altitude combinations.  Refer to the Ability to Maintain Level Flight chart in Chapter 24.  When possible; a landing site should be selected that provides a smooth hard surface and be approached at a safe single or dual-engine airspeed. 

1.  Prelanding and landing checklist—Complet(ed). 

2.  Arrive at 90 degree position at about 350 feet AGL; 60-80 KIAS; with maximum Nr. 

3.  At about 1000 feet straightaway into the wind; continue descent so as to arrive at approximately 75 feet AGL at or above single or dual engine airspeed. 

4.  Once landing is assured; commit to landing by initiating a nose up flare.  Maintain flare until about 30 feet AGL. Apply collective to cushion the landing.

NOTE: Single or dual engine landings to confined areas or unprepared terrain may require a slight modification of final approach flare and airspeed to clear obstacles and/or lessen ground roll at touchdown. 

5) At 30 feet AGL; reduce nose attitude to a maximum of 8 degrees noseup and increase collective to cushion landing.

6) Upon ground contact; slowly lower collective pitch lever to minimum and simultaneously move cyclic slightly forward of neutral position.

7) Apply wheel brakes to minimize ground roll. 

12.10

SINGLE- OR DUAL-ENGINE FAILURE IN FLIGHT

• Pilot response to single-or dual-engine failure Is dictated by gross weight; ambient conditions; relative wind; and height above the surface. These factors will determine whether an immediate landing or a flyaway recovery should be attempted.  Based on the pilot's knowledge of aircraft single- or dual-engine power available and power required; the pilot should decide which procedure he intends to follow before the emergency occurs.  Indecision following the single- or dual-engine failure may prevent the success o either procedure.

• If the altitude hold feature of AFCS is engaged; It will increase collective pitch in an attempt to hold altitude.  The collective must be positively controlled by the pilot to prevent excessive loss of rotor speed.

• Jettison of Auxiliary Fuel Tanks at rates-of-descent greater than 1500 fpm and forward airspeed greater than 120 KIAS may result In aircraft or rotor strike due to the earodynamic and stability characteristics of jettisoned tanks.  The risk of an aircraft strike is highest for empty tanks.  Jettison characteristics improve with increasing auxiliary fuel tank weight(fuel state)

• Nose High attitudes shall be avoided near the surface or the tail rotor blades will strike the ground or water. Tail rotor contact may occur with nose attitudes above 5 degrees when on the water.

• If altitude cannot be maintained or a safe single- or dual-engine landing is not feasible; decrease gross weight by releasing external cargo; dumping fuel; or jettisoning auxiliary fuel tanks if required.  Stop dumping before landing.

• Careful monitoring of main fuel tank quantities is required on flights where fuel transfer from range extension fuel tanks is being conducted; and fuel is not being depleted from all main tanks.  Main fuel tank expansion volume can diminish and ultimately result in overboard vent spillage due to constant flow of fuel through helicopter fuel system precheck lines.

*1. Collective--Maintain Nr.

*2. Airspeed--As required.

*3. Pickle--External load as required.

*4. Tanks--Jettison as required.

*5. Speed control levers--As required (shut off affected engine, conditions permitting).

6.  Land as soon as practical.

• A roll on landing will normally decrease power required. Minimize drift and determine yaw on landing.

• Determine which engine has failed by reference to engine torquemeters, T5 indicators, Nf or Ng tachometers, and proceed as instructed in Engine Shutdown In Flight in this section. If a restart is advisable, refer to Engine Restart In Flight in this chapter.

12.11

POWER MALFUNTIONS 

FIGURE 12-2

COMPRESSOR STALL

Indications: T5 -increasing 

                                                  All other parameters - decreasing

Note

Compressor stall Is normally accompanied by unusual engine sounds/slight yaw kick.  Illumination of ENGINE UEL BOOST and FUEL FILTER CAUSTION lights is possible due to decay of Ng.

*1. Collective—Maintain Nr.

*2. Airspeed—As required.

*3. Pickle—External load as required.

*4. Tanks—Jettison as required.

*5. Speed control levers—As required. (If compressor stall of No.2 eng is indicated immediately secure SCL and continue with Engine Shutdown in Flight procedures.  If No.1 or No.3 engines; affected SCL below MIN GOV)

WARNING

With a compressor stall in the No.2 engine; any delay in shutdown of the engine can result in hot exhaust gas backflow intothe engine compartment; creating a fire hazard.

6. If T5 continues to rise; position speed control of affected engine to SHUT OFF; secure engine as instructed under Engine Shut Down In Flight in this chapter.

7. If T5 decreases and stall clears; slowly advance speed control lever to reestablish matched torques.

8. I stall recurs; secure affected engine as instructed under Engine Shutdown in Flight in this chapter.

12.11

POWER MALFUNCTIONS

ENGINE POWER LOSS

SYMPTOMS

1. Power loss caused by control/accessory malfunction; not stall; no flameout. Under certain conditions an Nf flex shaft failure will cause the affected engine to stabilize at ground idle with no control available through the speed control lever.

2. Power loss caused by fuel contamination/fuel starvation (engine flameout)

*1. Collective—Maintain Nr.

*2. Airspeed—As required.

*3. Pickle—External load as required.

*4. Tanks—Jettison as required.

*5. Speed control levers—As required.

*6. Continue to use affected engine if engine is producing some torque and all engine parameters are within limits.

WARNING

If the No.2 engine is operating at a low power condition and the Ng is less than 75%; hot exhaust gas may backflow into the engine compartment creating a fire hazard. Limit airspeed to less than 85KIAS to reduce backflow. If dual-engine flight can be maintained; consideration should be given to securing the No.2 engine.

7. Carefully monitor all engine parameters.

8. Secure affected engine as instructed under Engine Shutdown in Flight in this chapter if any further engine malfunction is indicated; or if affected engine is not producing torque.

Note

If engine power loss takes place following fuel system transfer; selected fuel source is suspect for contamination or insufficient fuel.

12.11

POWER MALFUNTIONS  

FIGURE 12-4

ENGINE OVERSPEED

Engine may accelerate to maximum power.  If engine attempts to deliver uncommanded power exceeding the total torque requirements; Nf/Nr will increase /overspeed depending on the degree of power surplus.  Also; if the engine attempts to deliver uncommanded power less than the total torque requirements; Nf/Nr can be expected to increase slightly; about 1% to 2%.

*1. Collective—Maintain Nr.

*2. Airspeed—As required.

*3. Pickle—External load as required.

*4. Tanks—Jettison as required.

*5. Speed control levers—As required. Attempt to regain control of affected engine power by retarding affected engine speed control lever below MIN GOV.

WARNING

If the No.2 engine speed control lever is at or below MIN GOV and the Ng is less than 75%; hot exhaust gas may backflow into the engine compartment; creating a fire hazard.  Limit airspeed to less than 85 KIAS to reduce backflow. If dual-engine flight can be maintained; consideration should be give to securing the No.2 engine.

6. If affected engine cannot be controlled manually without exceeding operating limits secure engine as instructed under Engine Shutdown in Flight.

7. If speed control lever can be used to control affected engine power without exceeding operating limitations; use it to match engine torques.  Make all collective adjustments slowly to facilitate maintaining torques matched.

Following an Nf flex shaft failure; the SCL will act as a direct throttle in the transition range; providing full control of engine power. Control may or may not be regained with a fuel control malfunction.

8. Make a normal landing IAW Normal Landing procedures in Chapter 7 except copilot will do as follows; as directed by pilot:

a. Control Nr throughout descent and approach by adjusting SCL of malfunctioning engine.  b. While reducing collective landing; retard speed control lever on malfunctioning engine to prevent rotor overspeed.

12.11

POWER MALFUNCTIONS

FIGURE 12-5

CONTROL LINKAGE FAILURE

1. Speed control lever disengaged.

    

   CORRECTIVE ACTION:

1. Match torques using normal engine speed control levers

2. If Nr exceeds desired limits; reduce speed control lever position on normal engine(s) to decrease Nf/Nr.

3. Use fuel selector lever of affected engine(s) to secure engine.

2. Collective compensation linkage (collective bias) disengaged.

a. Reduced torque response on affected engine with change in collective position.

b. Noticeable torque split with change in collective position

c. Rotor droop with increased collective input.

     CORRECTIVE ACTION:

1. Trim engine speed control levers to maintain Nf/Nr.

2. Retrim; with load change; as necessary.

 Note

Expect unusually large torque splits at high load conditions.

12.11

POWER MALFUNTIONS

FIGURE 12-6

POWER TRAIN FAILURE

Fail between Nf & NGB

a.Sudden increase to zero  on Nr & torque.

b.Ng & T5 increaseing until overspeed system actuation, then decrease to flight idle

c. Grinding/howling noise

Fail of transmission system

1. Ng,T5-decrease/ Torque to zero.

2. Nf-increase to overspeed, then stabilizes at flight idle.

*1. Collective—Maintain Nr.

*2. Airspeed—As required.

*3. Pickle—External load as required.

*4. Tanks—Jettison as required.

*5. Speed control levers—As required. (secure engine(s))

CAUTION

Do not attempt to restart affected engine.

POWER MALFUNTIONS

FIGURE 12-7

POWER DETERIORATION

1. Extended hover over salt water.

1. Record low power indications for maintenance action.

2. Increase hover altitude to reduce salt buildup/power reduction rate.

3. Abort mission if power deterioration is excessive.

A T5 increase of 40 degrees Celsius at a constant Q is equal to a power loss of about 40%.

2. Compressor fouling

1. Record low power information for maintenance action.

2. Abort mission if power deterioration is excessive.

3. Compressor and turbine erosion/FOD.

1. Record unusual symptoms and power data for maintenance action.

2. Abort mission if power deterioration is excessive.

4. Stator vane schedule shift

1. Record unusual symptoms and power data for maintenance action.

2. Abort mission if power deterioration is excessive.

2. Excessive engine air bleed/leakage.

1. Record unusual symptoms and power data for maintenance action.

2. Turn anti-icing system of low-power engine ON; look for slight increase in T5. Turn system OFF; look for slight decrease in T5. If T5 remains steady; anti-ice system is inoperative

2. Abort mission if power deterioration is excessive

POWER MALFUNTIONS

FIGURE 12-8

ENGINE LUBRICATION SYSTEM MALFUNCTIONS

1. ENG OIL PRESS HIGH caution light on:  (a) Cold oil / (b) Plugged lube jet

1. Maintain reduced speed/power on affected engine until engine oil temperature is within normal operating range

1. If critical power requirements exist; reduce power of affected engine to minimum needed for immediate requirements.

2. Transition to single- or dual-engine operating procedures as quickly as possible; and secure affected engine as instructed under Engine Shutdown in Flight in this chapter.

2. ENG OIL PRESS LOW caution light on  (NOTE: Low pressure light may come on at ground idle if Ng is at or near minimum limit.)

1. If critical power requirements exist; reduce power of affected engine to minimum needed for immediate requirements.

2. Transition to single- or dual-engine operating procedures as quickly as possible; and secure affected engine as instructed under Engine Shutdown in Flight in this chapter.

3. High oil temperature (NOTE: Oil temperature may approach maximum limit during sustained high load condition at high ambient temperatures.)

1. Reduce power of affected engine to minimum needed for immediate requirements.

2. If engine oil temperature decreases to within maximum limit; continue to operate affected engine at reduced power.

3. If engine oil temperature continues to exceed maximum operating limits; transition to single- or dual-engine operating procedures as quickly as possible; and secure engine as instructed under Engine Shutdown in Flight in this chapter.

4. Engine oil low level caution light on.

1. Replenish from auxiliary oil tank

.-Level single- or dual-engine flight and/or safe single- or dual-engine hover landing may not be possible at certain combinations of helicopter gross weight and density altitude. Flight conditions may require that the decision to establish single- or dual-engine flight be deferred until a sfe descent is possible. Select landing site suitable for running landing if available.      -If the No. 2 engine must be operated at less than 75% Ng; hot exhaust gas may backflow into the engine compartment creating a fire hazard.  Limit airspeed to less than 85KIAS to reduce backflow. If dual-engine flight can be maintained; consideration should be given to securing the No. 2 engine.

12.12

ENGINE CHIP LOCATOR LIGHT

An engine chip locator light accompanied by unusual vibrations and/or low oil pressure/high oil temperature; or an engine chip locator light returning after resetting circuit breaker without the above indications; is cause to suspect probable engine failure.  If an engine chip detector light goes on; do this:

*1. Instruments/caution lights--Check

If secondary indications are present (vibrations/low oil pressure/high oil pressure)

*2. Perform Single- or Dual-Engine Failure procedures.

If chip locator light is not accompanied by secondary indications”

*3 pull and reset engine chip circuit breaker 

If chip locator light returns are circuit breaker is reset:

4. Perform Single- or Dual-Engine Failure Procedures.

If chip locator light remains off:

 5. Continue mission; monitoring engine performance closely.

WARNING

Level single- or dual-engine flight and/or safe single- or dual-engine hover landings may not be possible at certain combinations of helicopter gross weight and density altitude.  Flight conditions may require that the decision to establish single- or dual- engine flight be deferred until a safe descent s possible.  Select landing site suitable for running landing if available.

12.13

EMERGENCY SHUTDOWN

If an engine situation such as fire; control failure; etc. dictates immediate discontinuation of engine or rotor system operation; stop the aircraft if moving; request assistance as necessary; and proceed as follows:

*1.  High pressure rotor brake switch--EMER.

*2.  All engine speed control levers--SHUT OFF.

*3.  APP--As required.

*4.  Fuel selector levers--SHUTT OFF.

WARNING

• A fire hazard exists during emergency brake application due to the heat generated and the presence of debris and oil in the rotor brake area.

• Personnel should not exit the cabin section during emergency shut down until rotor has stopped.

Note

• Under frequency protection may cause loss of electrical power due to rapid Nr decay prior to complete pressurization of the emergency rotor brake.

12.14

ENGINE SHUTDOWN IN FLIGHT

*1. Speed control levers--Shut off. If No. 2 engine is being secured, reduce airspeed to less than 85 KIAS.

WARNING

• If an operating engine and a failed or secured engine have the same tank selected; the operating engine may flame out if the failed or secured engine fuel selector lever was not placed to SHUT OFF

• Failure to reduce airspeed to less than 85 KIAS when securing the No. 2 engine increases the hot exhaust backflow component and likelihood of a subsequent engine compartment fire.

*2. Fuel selector lever--Shut off.

CAUTION

• If an engine post shutdown fire should occur; as indicated by a continuous T5 above 320 degrees Celsius; motor engine with starter to extinguish fire.

3. Adjust power on operating engines.

4. EAPS door--Closed.

12.15

ENGINE RESTART DURING FLIGHT

Failure to reduce airspeed to less than 85 KIAS when securing the No. 2 engine increases the hot exhaust backflow component and likelihood of a subsequent engine compartment fire.

If at least 30 seconds of gas generator windmilling with the speed control lever at SHUT-OFF is not provided, the possibility of a hot start increases due to fuel accumulation and excess fumes.

The No. 2 ENGINE OVERHEAT caution light may illuminate for a short time (up to 30 seconds) during restart of the No. 2 engine at any airspeed. Monitor engine state for hot or hung starts. If a hot or hung start is experiences, immediately secure engine.

1. Emergency start switch--EMER.

2. EAPS--Closed.

3. Engine speed control lever--SHUT OFF. Inoperative engine.

4. Fuel selector lever--As required.

Due to probability of damaging the starting system, if time permits; the gas generator speed should be at zero before engaging the starter.

5. Starter button--Press.

6. Speed control lever--GRD IDLE at 20% Ng.

7. Engine instruments--Checked.

While engine is accelerating; check Ng tachometer; T5 indicator; and engine fuel flow; as during normal start.

8.Speed control lever--100% Nf. Match engine torques.

9. EAPS--As desired.

12.16.3

THREE-ENGINE FAILURE

(HOVER / TAKEOFF)

*1.  Collective--Reduce (if altitude permits, to maintain Nr).

*2.  Airspeed--As required

*3.  Pickle--External load as required.

*4.  Tanks--Jettison as required.

*5.  Speed control levers--As required.

*6.  Collective—Increase (cushion landing)

12.16.4

THREE-ENGINE FAILURE

(CRUISE)

*1.  Collective--Reduce (to maintain Nr at 95-100%

*2.  Airspeed--As required (maximum glide distance airspeed provides improved flare effectiveness).

*3.  Pickle--External load as required.

*4.  Tanks--Jettison as required.

*5.  Speed control levers--As required.

*6.  Execute autorotative landing.

12.17.1.1

TAIL ROTOR DRIVE SYSTEM FAILURE (HOVER AND TAKEOFF)

*1. Collective--Reduce (if altitude permits) to initiate a moderate rate of descent and retard rotation.

*2. Airspeed--As required (land in level attitude).

*3. Pickle--External load as required.

*4. Tanks--Jettison as required.

*5. Speed control levers--Shut off at 5 to 20 feet AGL.

*6.  Collective--Increase (cushion landing).

12.17.1.2

TAIL ROTOR DRIVE SYSTEM FAILURE (CRUISE)

*1. Collective--Reduce (enough to stop fuselage rotation).

*2. Airspeed--100 to 120 KIAS.

*3. Pickle--External load as required.

*4. Tanks--Jettison as required.

*5. Rudder pedals--Centered.

*6. If directional control is not regained--Autorotate.

If the tail rotor/tail rotor gearbox/tail section has (have) departed the aircraft; absence of the autorotating tail rotor will necessitate an autorotative descent and landing.  However; due to the forward shift of cg under such conditions; the pilot should use extreme caution during the flare recovery to avoid excessive forward pitch rates which may become uncontrollable.

7. Secure all engines before increasing collective to cushion the landing.

8. If directional control is regained; proceed with steps a and b.

• Alter bank angle and collective as required to maintain controllable flight.  The magnitude of bank angle required for straight ground track will vary with airspeed and collective setting.  As airspeed is reduced below 100 to 120 KIAS; a larger angle of bank or reduction in torque will be required to compensate for increased right yaw.

• Land as soon as possible.

  1. If over suitable flat terrain; attempt a running landing.  Consideration should be given to landing with the landing gear up if the surface is soft/uneven and possibility of shearing the landing gear or rolling over Is judged to exist. Establish 80 KIAS on final and approaching 50-75 feet AGL; a combination of collective reduction/aft cyclic will minimize torque and slow groundspeed to assist in aligning the nose for touchdown.  Secure all engines before increasing collective to cushion landing.

  2. (Paraphrased for Space) If not aligned with terrain, side flare

12.17.1.3

TAIL ROTOR DRIVE SYSTEM FAILURE DURING LANDING

If the tail rotor drive system fails during the landing approach, the proper corrective action will depend upon the airspeed and altitude the helicopter has at the time of failure. The pilot should land the helicopter utilizing either the Tail Rotor System Failure (Cruise) landing procedure or the Tail Rotor Drive System Failure (Hover and Takeoff) landing procedure in this chapter. It is, therefore, incumbent upon the pilot to select the proper procedure based upon where the helicopter is in the landing profile.

12.17.2

 TAIL ROTOR CONTROL SYSTEM FAILURE

The self-centering spring installation provides the capability of continued flight to a landing site with tail rotor control system failure.  At a gross weight of 46500 lbs the helicopter flies in a right sideslip (left yaw) below 135 KIAS; trims to balanced level flight at about135 KIAS; and flies in a left sideslip (right yaw) at speeds above 135 KIAS.  Balanced flight at gross weights above 46500 lbs is achieved at lower airspeeds; and below 46500 lbs at higher airspeeds.

12.17.2.1

 APPROACH AND LANDING WITH TAIL ROTOR CONTROL SYSTEM FAILURE

If an approach and landing is to be made; a/s can be reduced while maintaining a reasonable trimmed flight condition by slowly reducing power and entering a left turn with cyclic.  Balanced flight can be maintained during power and airspeed changes by increasing or decreasing the roll angle until about 35-40% Q and 50-60 KIAS is attained.  Level flight can then be maintained with a small amount of right sideslip at 35-40% Q and 50-60 KIAS.  Increasing collective too rapidly or too much will cause a sideslip to the left and decreasing collective too rapidly or too much will cause a sideslip to the right.  It is recommended that a roll-on landing be made on a prepared surface.  If the landing has to be made to an unprepared surface; consideration should be given to a wheels-up slide-on landing.  it is Important during the final phase of the landing to (1) retain attitude by referencing the VGI; (2) slightly apply collective just before touchdown to provide a nonslip condition for touchdown; and (3) immediately apply wheel brakes while slowly lowering the collective.  A wave-off may be made any time before a small flare Is initiated for final touchdown by accelerating into forward flight. While accelerating; the helicopter will enter a left sideslip condition that will decrease as airspeed Is increased.

1. Flightpath--180 degree left approach

2. Downwind leg--200' altitude and 45-50 KIAS.

NOTE: Airspeed can be reduced during the turn on to final approach or when rolling out of the turn to final approach.

3. Start--APP.

NOTE: Nr above 103% may result in APP shutdown.

4. Final approach--6-8 degree nose-up attitude; and enough torque to maintain 35-45 KIAS and 200-300 fpm rate of descent.

WARNING: Rapid or too large increased collective application will cause the helicopter to sideslip to the left.  Rapid or too large collective application will cause the helicopter to sideslip to the right

5. Collective--Increase slightly to reduce sideslip and maintain all conditions to touchdown.

6. Touchdown--Immediately apply wheel rakes and slowly lower collective.

7. Speed control levers--GROUND IDLE.

12.17.2.2

 TAIL ROTOR CONTROL SYSTEM FAILURE IN A HOVER

Loss of tail rotor control in a hover will be characterized by unresponsive pedals.  Aircraft response will depend on hover power required; wind speed; and aircraft heading relative to the wind.  Collective increases will increase right yawing moment.  Collective decreases will decrease the right yawing moment.  If the aircraft is yawing right; slowly reduce collective and touch down with minimum drift as tail yaws into the wind.  If aircraft is yawing left; start the APP if possible and slowly decrease Nr at 5 to 10 feet AGL to reduce tail rotor thrust and left yaw rate.  Touch down with minimum drift as tail yaws into wind and left yaw rate stops.

12.17.3

PYLON UNSAFE FOR FLIGHT LIGHT

If illumination of the PYLON UNSAFE FOR FLIGHT light while operating at 100%Nr may provide warning of a malfunctioning tail rotor disconnect fitting.  Total failure of the tail rotor disconnect fitting will result in loss of tail rotor drive.  Failure to retract or premature extension of the tail rotor actuator could result in damage to the tail rotor head or tail rotor gearbox.  Extension or cycling of the tail rotor disconnect disengage flag may also indicate malfunctioning tail rotor disconnect fitting.

If illumination of the PYLON UNSAFE FOR FLIGHT light or extension/cycling of the tail rotor disengage flag occurs; execute the following procedures:

*1. If accompanied by abnormal vibration; noise in the tail section; or yaw kick--Land immediately.

*2. If not accompanied by these indications--Land as soon as possible; minimize tail rotor stress; execute running landing if possible.

Note

A PYLON UNSAFE FOR FLIGHT caution light may be accompanied by loss of AFCS servos.

12.18

SWASHPLATE BEARING VIB DETECT, BEARING VIB LIMIT, BEARING TEMP DETECT, AND BEARING TEMP LIMIT CAUTION LIGHTS

If the VIB DETECT bearing status light illuminates:

1. Aircrew — Alert.

a. Record sensor location and time of occurrence.

2. Perform BMS reset procedure.

3. If VIB DETECT bearing status light returns during the  same flight — Land as soon as practical.

4. If light does not come on again, resume routine monitoring.

NOTE

• Should a VIB Detect occur on SP-1 and/or SP-2 and the system is reset, a subsequent VIB Detect on DISC is unrelated and another system reset maybe performed. The same applies to an initial VIB Detect on DISC with a subsequent VIB Detect on SP-1 and/or SP-2. Do not reset the BMP if a second VIB Detect occurs at the same location (swashplate or disconnect).

• For purposes of this procedure, a flight is defined as the period between rotor engagement and rotor shutdown.

   

If the BEARING VIB LIMIT caution light comes on:

1. Aircrew — Alert.

2. Land as soon as practical.

Aircrew:

1. Emergency landing checklist — Execute.

If the BEARING TEMP DETECT caution light comes on:

1. Aircrew — Alert.

*2. Land as soon as possible.

Aircrew:

1. Emergency landing checklist — Execute.

If the BEARING TEMP LIMIT caution light comes on:

1. Aircrew — Alert.

*2. Land immediately.

Aircrew:

1. Emergency landing checklist — Execute.

12.20

BIM CAUTION LIGHT

If BIM® caution light goes on, have a crewmember check if BIM® circuit breaker is in (on right cabin circuit breaker panel). Due to the sensitivity of the system, the caution light may go on due to Electromagnetic Interference (EMI), giving the pilot a false indication of impending spar failure. If the caution light remains on with the circuit breaker in, and EMI is not verified:

In Flight:

*1. Airspeed — 80 KIAS, minimize maneuvering.

*2. Altitude — Minimum safe.

3. No. 3 primary AC BIM® circuit breaker — Check in.

4. Land as soon as practical. Do not exceed 1.5 flight hours unless necessary to reach a safe landing site.

a. If flying with an external load that cannot be safely transported at 80 KIAS, consideration should be

given to load jettison. Hover flight should be minimized.

WARNING

Flight operations outside a level cruise flight regime of 80 ±5 KIAS and operations in a hover produce blade flight loads that will increase potential crack stresses and accelerate crack propagation rates. Continuous flight outside this recommend flight profile will compromise the safety margin incorporated into the maximum prescribed flight duration and lower the allotted 1.5 hour interval.

On the Ground:

If all spar indicators are white, but the BIM® caution light remains on or the IBIS BIT is unsatisfactory, a malfunction

in the radiation detector or signal processor is indicated. The helicopter may be flown for 1.5 hours at 80 KIAS

at minimum safe altitude (minimizing maneuvering). The helicopter must then be landed and re-inspected before

continuing on additional 1.5-hour legs. If a spar indicator shows black at any time, further flight shall not be attempted

until qualified maintenance personnel check the integrity of the spar.

12.21.1

 Engine Compartment Fire(s) on the Ground

If an engine compartment fire occurs while on the ground, do this:

*1. Speed control levers — As required (affected engine(s) shut off).

*2. Engine emergency T-handle(s) — Pull aft (affected engine(s)).

*3. Main engine fire extinguisher switch — Main, reserve if necessary.

4. Groundcrew — Alerted.

Aircrew:

*1. Notify pilot of location and extent of fire.

*2. Discharge fire extinguisher into compartment access.

12.21.2

Single- or Dual-Engine Compartment Fire(s) in Flight

*1. Collective — Maintain Nr.

*2. Airspeed — As required.

*3. Pickle — External load as required.

*4. Tanks — Jettison as required.

*5. Speed control levers — As required (affected engine(s) shut off).

*6. Engine emergency T-handles — Pull aft (affected engine(s)).

*7. Main engine fire extinguisher switch — Main, reserve if necessary.

Note

If two bottles were discharged into one engine compartment, the remaining bottle can be discharged into either of the remaining compartments. The last bottle will be discharged by either the MAIN or RESERVE selection, depending on which two bottles have already been discharged, and which compartment has been selected. In this case, the most expeditious thing to do is to select MAIN and then RESERVE.

*8. If fire continues, land immediately.

9. If fire extinguished, refer to Single- or Dual-Engine Failure in this chapter.

12.21.3

Engine Post-shutdown Fire

An engine post-shutdown fire in the combustion chamber after shutdown may continue to feed itself unless it is blown out by compressor air. Indications would be a rise in T5 above 320 °C after shutdown and/or excessive smoke from the engine exhaust outlet.

*1. Speed control lever — SHUTOFF.

*2. Fuel selector lever — SHUTOFF.

*3. Emergency start switch — EMER.

*4. Starter button — Press. Motorize engine until fire is put out, and observe T5.

Note

If all engines have been shut down, APP should be operating.

5. If fire continues, be sure EAPS doors are open and have fire extinguisher discharged into air inlet duct while

motoring engine.

6. Pull down on handle of speed control lever to stop starter.

If an engine fire warning light goes on:

7. Emergency T-handle — Pull aft to select engine compartment for fire extinguisher.

8. Engine fire extinguisher switch — Main. Reserve, if necessary.

Aircrew:

*1. Notify pilot of location and extent of fire.

*2. If fire continues, after engine has been motorized, at pilot command, discharge fire extinguisher through

open EAPS doors.

12.21.4

Three Simultaneous Engine Compartment Fires in Flight

*1. Land immediately.

12.21.5

 APP or Cabin Heater Fire

A fire in either the APP or cabin heater will be indicated by the fire warning master lights and the fire warning lights in the APP emergency T-handle. Whenever the APP and cabin heater fire warning light is on, do this:

*1. APP emergency T-handle — Pull aft (to discharge fire extinguisher and shut off APP and heater fuel).

*2. If fire persists — Land immediately.

3. APP circuit breaker control switch — Off (if APP operating).

4. Cabin heater rheostat control — Off (if cabin heater operating).

5. Alert ground crew (if on the ground).

Aircrew:

*1. Notify pilot of location and extent of fire.

*2. Discharge fire extinguisher into compartment access.

12.21.6

Fuselage Fire

*1. Transfer selector switches — Close.

*2. Purge pushbutton — Off.

*3. Cockpit circular vents — Closed.

*4. Vent fan switch — Off.

*5. If fire persists — Land immediately.

Aircrew:

*1. Notify pilot of location and extent of fire.

*2. Pull circuit breaker(s) for affected system at pilot command.

*3. Fight fire with fire extinguisher.

*4. Emergency Landing Checklist — Execute.

12.21.7

Electrical Fire

WARNING

Turning all generators off will result in immediate loss of all electrical instruments, warning systems, ICS, and AFCS, except servo 1. Helicopter response to total electrical loss may be violent. Landing gear may only be extended by the emergency method, and a positive gear down check will not be possible. Consideration should be given to all problems before turning all generators off.

*1. Circuit breaker (for affected circuit) — Pull.

*2. Fight fire with portable fire extinguisher.

*3. If fire persists — Land immediately.

Aircrew:

*1. Notify pilot of location and extent of fire.

*2. Pull circuit breaker(s) for affected system at pilot command.

*3. Fight fire with fire extinguisher.

*4. Emergency Landing Checklist — Execute.

12.21.8

Hydraulic Fire in Main Rotor Pylon

*1. Land immediately.

Note

If feasible, accomplish a running landing at 40 knots ground speed to maintain airflow through the rotary wing pylon.

*2. Perform Emergency Shutdown procedure.

WARNING

Delay in shutting down the helicopter may give the fire time to burn through a flight control component, causing the helicopter to roll over.

3. Portable fire extinguisher — Use.

12.21.9

Smoke and Fume Elimination

Pilot:

1. Vent fan — On.

2. Registers and diffusers — Open.

Crewman:

1. Cabin diffusers — Open.

2. Upper half of personnel door — Open.

3. Emergency escape hatch (gunner window) — Open.

4. Cargo ramp door — Open.

Caution

Do not push out cabin windows or escape hatches while helicopter is in flight, as they may damage helicopter.

12.21.10

Fire During Rapid Ground Refueling (RGR) Operations

Aircrew:

*1. RGR personnel — Alerted.

*2. Refueling operations — Cease.

*3. Emergency shutdown — As required.

*4. Evacuate helicopter.

*5. Fight fire with portable fire extinguisher.

Groundcrew:

1. Refueling switch — Off.

2. Fuel line — Disconnect.

3. Alert aircraft/vehicle personnel.

4. Fight fire with portable fire extinguisher.

12.21.11

No. 2 ENGINE OVERHEAT Caution Light

Note

The No. 2 ENGINE OVERHEAT light may illuminate for a short time (up to 30 seconds) during restart of the No. 2 engine at any airspeed. Monitor engine start for hot or hung starts. If a hot or hung start is experienced, immediately secure engine.

*1. Collective — Maintain Nr.

*2. Airspeed — As required.

*3. Pickle — External load as required.

*4. Tanks — Jettison as required.

*5. Speed control levers — No. 2 engine shutoff.

6. Perform Single- or Dual-Engine Failure procedures.

7. If subsequent fire is detected / suspected, perform Single- or Dual-Engine Compartment Fire(s) in Flight procedure.

12.23.1.1

Fuel Filter Bypass Light

Three engine fuel filters being bypassed:

*1. Engine instruments — Monitor.

*2. Land — As soon as possible.

One or two engine fuel filters being bypassed:

1. Engine instruments — Monitor.

2. Land — As soon as practical.

12.23.1.2

Engine-Driven Fuel Pump Failure

If an engine-driven fuel pump should fail, the engine will shut down due to fuel starvation. Refer to Engine Shutdown in Flight in this chapter.

12.23.1.3

 Fuel Boost Pump Failure

If a fuel boost pump should fail (as evidenced by an ENG FUEL BOOST caution light and its associated ENG FLTR BYPASS caution light), the engine-driven fuel pump will supply enough fuel for normal engine operation. Check engine operation and fuel flow.

Land as soon as practical.

12.23.1.5

Fuel Transfer Failure

If one auxiliary fuel tank fails to transfer into any main fuel tank, the following procedure is recommended to reduce asymmetrical fuel loading as much as possible: Operate two engines from the main tank (No. 1 or No. 3) on the non-transferring side. Transfer fuel from the operating auxiliary tank to the main tank on the non-transferring side. When the transferring auxiliary tank is empty, the pilot may elect to jettison or retain the auxiliary tanks. If the pilot elects to retain the auxiliary tanks and asymmetrical fuel loading is still present, continue to operate two engines from the selected main tank until that tank FUEL LOW caution light goes on. If asymmetrical fuel loading is still present, operate two engines from the No. 2 tank.

                               WARNING

Fuel quantities should be watched closely during this procedure to prevent flameout.

           Note

Fuelconsumptionfromthetankscanbeincreased ordecreasedselectivelybyvaryingenginepower.

Whenoperatingwithoneemptyauxiliaryfueltankandonefullone,aircraft handlingcharacteristicsremainsatisfactory.

12.23.2

Auxiliary Fuel Tank Jettison

*1. Airspeed — 0 to 150 knots. (Maximum airspeed in descent: 120 knots.)

*2. Rate of descent — Less than 1,500 feet per minute.

*3. Bank angle — 0°.

*4. Area — Cleared if possible.

*5. Place desired AUX TANK JTSN switch — ON.

12.23.3

 Fuel Dump

Fuel dumping may be required in case of single- or dual-engine operation, or to adjust fuel loading in case of fuel system malfunction. Fuel shall not be dumped below 90 KIAS or above 130 KIAS. Fuel shall not be dumped if the rate of descent is greater than 1,500 feet per minute. The desired minimum altitude for fuel dump is 6,000 feet.

1. Airspeed — Between 90 and 130 KIAS.

2. Rate of descent less than 1,500 feet-per-minute.

3. Avoid populated areas.

4. Determine desired fuel to remain after dumping.

5. AN/ALE-47(V) CMDS MODE switch — STBY (if the AN/ALE-47(V) is armed).

WARNING

If the CMDS MODE switch is not in the STBY or OFF position during fuel dumping procedures, inadvertent flare dispensing can ignite the aerosolized dumped fuel, which can result in a catastrophic fire.

6. Fuel dump switches — As required.

WARNING

Dumping fuel outside of NATOPS parameters and during high rates of descent may result in a catastrophic fuselage fire.

7.     Fuel quantity — Monitor.

8.     Fuel dump switches — Secure when desired tank level reached.

If fuel dump is not secured, it will dump down to the level that turns the fuel low-level caution  lights on, at which time fuel dump shuts off automatically.

Caution

After securing fuel dump switches, allow 2 minutes for fuel dump lines to drain. Securing fuel dump immediately before overflying a ship or landing area will result in fuel draining onto that ship or area, creating a personnel or a fire hazard.

9. Dump tubes — Check.

10. AN/ALE-47(V) CMDS MODE switch — As required.

12.23.4.1

AFCS Computer Malfunction

A malfunction in the AFCS computer can cause low to high random inputs into the main rotor or tail rotor controls, possibly resulting in helicopter vibration. The CMPTR POWER pushbutton on the AFCS CONTROL panel should be turned off if the following happens:

1. An increase in aircraft motion, vibration, or tip path plane movement accompanied by the AFCS DEGRADED advisory light and all FAIL ADVISORY lights except DESEN and SAS indicates a single computer (SIMPLEX) failure and the AFCS is only partially functional. If this happens, secure trim and

AFCS, then recycle computer power.

2. An increase in aircraft motion, vibration, or tip path plane movement accompanied by the AFCS CAUTION light indicates a dual-computer (DUPLEX) failure and no AFCS functions are available. If this happens, recycle computer power OFF and then ON.

An AFCS caution light means both computers are off and no AFCS functions are being performed. If recycling computer power OFF and then ON does not make the AFCS caution light go out, do the following:

*1. Instrument meteorological conditions (IMC) — Land as soon as possible.

2. Visual meteorological conditions (VMC) — Land as soon as practical.

12.23.4.2

 Desensitizer Failure

Any of the following conditions may indicate an inoperative desensitizer:

1. DSEN fail advisory light on the AFCS control panel is lit.

2. AFCS is off.

3. AFCS duplex failure.

4. FAS shearpin is sheared.

WARNING

Loss of a control desensitizer will, under certain circumstances, allow the pilot to interact with the fuselage bending modes to create a pilot-induced oscillation (PIO). This interaction can result in divergent helicopter oscillations. Delayed pilot response in eliminating these oscillations may result in helicopter damage and/or uncontrolled flight. If this happens, releasing the flight controls for several seconds should eliminate the condition. During external cargo operations, if PIO/PAO happens and cannot be controlled, immediately jettison the load.

If a desensitizer failure happens, do the following:

1. MODE RESET pushbutton — Reset.

If the desensitizer failure does not clear after mode reset, the following precautions must be taken:

1. Avoid abrupt control inputs.

2. Minimize hover time.

3. Do not pick up an external load. If flying with an external load, continue to the destination and gently set the load down. Do not attempt to re-lift the load.

12.23.4.4

AFCS Servo Hardover

An AFCS servo hardover is an uncommanded movement of the flight controls which cannot be easily overridden by the pilot. The rate at which the control moves may vary from a relatively slow rate (about 1 inch per second) to full travel in less than one second (100 percent per second). When potentially high rates of control change are experienced, and pressing the trim release does not override the drive, suspect an AFCS servo hardover. A rapid response to this emergency will be required to retain control. If a hardover is experienced, do the following:

*1. Transfer to other AFCS servo.

Caution

High control forces may change to normal at AFCS servo changeover.

*2. If servo hardover condition continues — Secure AFCS servos.

*3. If IMC — Land as soon as possible.

4. If VMC — Land as soon as practical.

5. If servo hard-over condition goes away — Proceed and land as soon as practical.

12.23.5.1

Alternating Current System Failure

1. Affected generator — RESET/OFF, then ON.

2. If one or two generators fail — Land as soon as practical.

3. If all generators fail or if two generators fail during night, instruments, or icing conditions — Land as soon as possible.

4. Failure of any generator with a simultaneous supervisory panel failure will result in loss of the associated primary AC bus. If this occurs during night or IMC — Land as soon as possible.

Note

When operating the aircraft with the No. 1 generator on, and the No. 2 and No. 3 generators off or failed, the No. 3 primary AC bus will be lost failing the No. 2 AFCS computer, AHRS, TACAN, VOR, all three BDHIs, and the radar altimeter. Additionally, for NO. 2 GEN, NO. 3 GEN, NO. 2 RECT, BIM®, C/G HOOK INOP caution lights and the AFCS control panel will display a simplex failure.

12.23.5.2

Direct Current System Failure

1. If either rectifier fails — Land as soon as practical.

2. Extend landing gear.

3. If both rectifiers should fail, or if either rectifier fails at night or during instrument conditions, land as soon as possible.

12.23.6.1

Hydraulic System Fluid Quantity Low

A display of very low hydraulic fluid quantity by the hydraulic fluid status gauge or the caution panel dictates the following action:

1. First and second stage hydraulic systems fluid quantity low — Land as soon as possible.

2. First stage and utility hydraulic systems fluid low — Land as soon as possible.

3. First or second stage hydraulic systems fluid low — Land as soon as practical.

4. Second stage and utility systems fluid quantity low — Land as soon as practical.

5. Utility hydraulic systems fluid quantity low — Land as soon as practical.

12.23.6.2

 Utility Hydraulic System Failure

If utility hydraulic system failure is indicated by either the UTILITY PRESS caution light or the pressure gauge is at zero or fluctuating near or below 1,000 psi, proceed as follows:

WARNING

Extended flight with utility hydraulic system failure is not recommended due to possible loss of first stage hydraulic system and subsequent loss of tail rotor control.

*1. Landing gear — Extend.

Caution

Should utility hydraulic failure occur with ramp at or below level position, ramp to ground contact may occur during landing.

*2. Land as soon as possible.

12.23.6.2.1

Utility Hydraulic Fluid Hot

Should the UTILITY OIL HOT light illuminate, proceed as follows:

1.     Hydraulic pressure and quantity gauges — Check.

2.     HEAT EXCH UTIL (NO 1 PRI DC BUS) and HEAT EXCHANGE UTILITY PWR (NO 1 PRI AC BUS) circuit breakers — Check.

a.   If either circuit breaker is out, attempt to reset only once. Go to step 3.

b.   If both circuit breakers are in when first checked, pull the UTIL OIL HOT (NO 3 PRI DC BUS) circuit breaker.

(1)  If the caution light extinguishes, the fluid has overheated.

(a)   Reset circuit breaker.

(b)   Ramp and overhead door — Cycle several times.

(c)   Landing gear — Cycle several times.

(d)   Go to step 3.

Note

Ramp shall not be lowered below the level position at airspeeds in excess of 120 knots.

(2)  If the caution light remains illuminated, the blower has overheated and shut down. Reset the UTIL OIL HOT circuit breaker. Then, pull the HEAT EXCH UTIL circuit breaker for 1 to 2 minutes to allow blower to cool and be restored.

(a)   If the caution light extinguishes while the HEAT EXCH UTIL circuit breaker is out, the fluid is not overheated. Restored blower operation is verified by the caution light remaining off when the circuit breaker is reset.

(b)   If the caution light remains illuminated, the fluid is overheated (in addition to the blower). After resetting the HEAT EXCH UTIL circuit breaker, the caution light will not go out until the fluid has cooled. If the caution light is on, proper blower operation can be verified by pulling and resetting the UTIL OIL HOT circuit breaker and noting the caution light momentarily goes off.

3. If pressure and quantity remain normal, yet the light remains illuminated — Land as soon as practical.

12.23.6.3

1st/2nd Stage Hydraulic System Failure

WARNING

•  Failure of first and second stages of flight control system will result in loss of control of helicopter.

•  Rapid or abrupt movement of flight controls with only one primary flight control hydraulic  system operating can result in control restrictions due to a reduction of pressure in operating system.

NOTE

•  Do not turn a flight control system off if a constant abnormally high pressure is indicated.  Land as soon as practical.

•  In case of loss of pressure in first or second stage hydraulic system, check that both  collective flight control servo switches are ON.

• In the event of a pending 2nd stage failure (pressure fluctuations), consideration should be  given to securing AFCS SERVO 1 to allow smooth operation of AFCS servo functions.

*1.     Reduce airspeed to 80 to 100 knots.

*2.     Land as soon as possible.

When the second stage hydraulic system is inoperative due to a loss of pressure, these systems or related components will also be  inoperative:

1.     The half of each primary tandem servo that is powered by the second stage hydraulic system;  when the second stage hydraulic system is turned off, the half of the tail rotor tandem servo that  is powered by the utility hydraulic system.

2.             Pitch, altitude, roll, and yaw channels of SERVO 1.

12.23.6.3.1

Second Stage Hydraulic

Fluid Hot

Should the 2ND STG OIL HOT caution light illuminate, proceed as follows:

1.     Hydraulic pressure and quantity gauges — Check.

2.     HEAT EXCH NO 2 (NO 2 PRI DC BUS) and HEAT EXCHANGE 2ND STAGE PWR (NO 2B PRI AC BUS) circuit

breakers — Check.

a.   If either circuit breaker is out, attempt to reset only once. Go to step 3.

b.   If both circuit breakers are in when first checked, pull the 2-STG OIL HOT (NO 1 PRI DC BUS) circuit breaker.

(1)  If the caution light extinguishes, the fluid has overheated. Reset the circuit breaker and go to step 3.

(2)  If the caution light remains illuminated, the blower has overheated and shut down. Reset the 2-STG OIL HOT circuit breaker. Then, pull the HEAT EXCH NO 2 circuit breaker for 1 to 2 minutes to allow blower to cool and be restored.

(a)   If the caution light extinguishes while the HEAT EXCH NO 2 circuit breaker is out, the fluid  is not overheated. Restored blower operation is verified by the caution light remaining off when the circuit breaker is reset.

(b)   If the caution light remains illuminated, the fluid is overheated (in addition to the blower). After resetting the HEAT EXCH NO 2 circuit breaker, the caution light will not go out until the fluid has cooled. If the caution light is on,proper blower operation can be verified by pulling and resetting the 2-STG OIL HOT circuit breaker and noting the caution light momentarily goes off.

3. If pressure and quantity remain normal, yet the light remains illuminated — Land as soon as practical.

12.23.6.4

Restriction or Binding in the Flight Controls

*1.     Check for any cockpit obstructions to the flight controls.

*2.     Reduce airspeed between 80 to 100 KIAS.

*3.     Minimize flight control inputs.

*4.     Land as soon as possible.

Aircrew:

5.     Visually inspect all cabin flight controls.

12.23.6.5

 Primary Tandem Servo Malfunction

WARNING

When the 1 STG M/R SERVO BYPASS caution light is observed after a utility hydraulic system failure, securing first stage flight control system will result in loss of tail rotor control. There are no interlocks to prevent turning off pressure to first or second stage hydraulic systems when a servo in the other stage is in bypass. Turning off pressure to the non-bypassed stage results in loss of control of the servo.

When a servo bypass caution light is observed, do not turn off the corresponding servo system unless there is a definite restriction of controls and do the following:

*1.     Airspeed — Reduce.

*2.     Land as soon as possible.

12.23.6.6

Tail Rotor Hydraulic

System Failure

The first stage flight control hydraulic system furnishes the necessary pressure to operate the first stage side of the tail rotor tandem servo. The first stage hydraulic quantity indicator and the caution light are the primary visual indication of loss of hydraulic fluid to the first stage system. The first stage hydraulic pressure gauge and caution lights are an immediate indication of a loss of operating hydraulic pressure to the first stage side of the tail rotor tandem servo. The utility hydraulic system furnishes the necessary pressure to operate the second stage side of the tail rotor tandem servo.  The utility hydraulic quantity indicator and the caution light are the primary visual indications of loss of hydraulic fluid to the utility system. The utility pressure gauge and caution lights are an immediate indication of loss of operating hydraulic pressure to the second stage side of the tail rotor tandem servo. The UTILITY T/R PRESS caution light goes on when utility pressure downstream of the second stage servo shutoff valve in the utility module drops below 1,500 psi.

WARNING

Do not shut off first stage flight control hydraulic pressure when there is no utility hydraulic pressure being furnished to the tail rotor tandem servo. Tail rotor control will be lost.

12.23.6.7

Tail Rotor Tandem

Servo Malfunction

The primary visual indications of tail rotor tandem servo malfunction are the 1 STG T/R SERVO BYPASS and 2STG T/R SERVO BYPASS caution lights that go on when the servo has malfunctioned in such a manner to cause it to bypass hydraulic pressure or it has lost system pressure.

When a tail rotor servo bypass caution light is observed, do not turn off the corresponding servo system unless there is a definite restriction of controls and perform the following:

*1.     Airspeed — Reduce.

*2.     Land as soon as possible.

12.23.9

Main Gearbox Failure

Impending MGB failure may be indicated by abnormal noise from the MGB, yaw kicks, torque fluctuations, and/or unusually high power settings for given flight conditions.

If impending main gearbox failure is suspected:

*1.     Instruments and caution lights — Check.

*2.     Land immediately.

WARNING

An increase in torque for a given flight condition is an indication of a main gearbox impending failure.

12.23.9.1

Main Gearbox Chip

 Locator Light

When the CHIP DETECTED caution light is accompanied by the MAIN GB chip locator light on the chip locator panel, progressive failure of the main gearbox may be occurring.

*1.     Instruments and caution lights — Check.

*2.     If malfunction verified by secondary indications — Land immediately.

*3.     If malfunction not verified with secondary indications — LAND AS SOON AS POSSIBLE. When flying over water, return to nearest ship or shore at a reduced airspeed and low altitude. The altitude should be sufficient to permit a quick flare if an en-route emergency water landing is necessary.

4.     If chip detector light extinguishes, continue with mission and closely monitor all main gearbox instruments and caution lights.

Note

There is a 30 second time delay relay incorporated into the main lubrication sump and auxiliary lubrication sump chip detector systems. The MAIN GB chip detector on the chip locator panel in the cabin is not affected by the 30 second time delay relay.

12.23.9.2

Main Gearbox Oil

System Failure

NOTE: It is not necessary to abort a flight as a result of losing the main gearbox auxiliary oil pump as indicated by the MGB AUX LUBE PUMP caution light going on. Continue mission monitoring all other main gearbox gauges, chip detector, and caution lights. Be sure condition is corrected before next flight.

(Edited for Space) If the MGB OIL PRESS caution light goes on and a complete loss of oil pressure is indicated, the gearbox has lost all primary means of lubrication. In this case:

*1. Airspeed — As required. (Minimum power required for flight)

*2. Altitude — Reduce.

*3. Land as soon as possible. Duration of flight not to exceed 30 minutes.

If the MGB OIL PRESS and the MGB AUX lube pump caution lights both illuminate and the MGB oil pressure drops rapidly or decreases below minimum, the main gearbox has lost all means of lubrication and an immediate landing shall be made. In this case:

*1.     Land immediately.

If an immediate landing cannot be made (due to flight conditions, such as IFR or high altitude), perform the following:

1.     Airspeed — Reduce to 80 KIAS or less.

2.     Retard No. 2 engine to GRD IDLE.

CAUTION: Excessive temperatures within the No. 2 engine compartment may occur in flight with the No. 2 engine at GRD IDLE.

3.     Commence a power-on descent.

4.     Land immediately using No. 2 engine if necessary during the landing.

WARNING: Loss of MGB oil pressure accompanied by an increase in noise, vibrations, yaw kicks, or power surges indicates MGB seizure is imminent.

A malfunction of the main gearbox or the oil cooling system that would cause improper or insufficient lubrication will be indicated by one or more of these symptoms:

1.     MGB OIL PRESS caution light goes on.

2.     MGB OIL HOT caution light goes on.

3.     Maximum or minimum indications on the main gearbox oil pressure and temperature gauges. If  any of these indications are noted:

*4.     Maintain reduced airspeed and low altitude.

*5.     Land as soon as possible.

6.     When flying over water, return to nearest suitable landing site at reduced airspeed and low altitude. Altitude should be sufficient to permit a quick flare if en-route emergency water landing is necessary.

If a change of MGB pressure out of normal operating range (50 to 65 psi), but not exceeding maximum or minimum limits:

*7.     Land as soon as practical.

12.23.9.3

Main Gearbox Oil Cooler

Blower Failure

A main gearbox oil cooler blower failure may be indicated by an abnormal noise or thump and short duration medium frequency vibration/buffet felt through the flight controls and airframe. Damage to the system components in the vicinity of the oil cooler blower may occur. An oil cooler blower failure will be accompanied by one or more of the following indications:

1.     Main gearbox oil temperature and pressure caution lights and abnormal gauge indications.

2.     No. 2 engine oil temperature gauge and pressure caution lights for abnormal indications.

Components or systems susceptible to secondary damage include 1st stage hydraulic system, tail rotor drive shaft, tail rotor control linkage, utility tail rotor control pressure and return lines, and the No. 2 engine.

If indication of a main gearbox oil cooler blower failure exists:

1.     Check appropriate instruments and caution lights.

2.     Shut down No. 2 engine (conditions permitting).

3.     Land as soon as possible.

12.23.9.4

 Free Wheeling Unit Failure

A Free Wheeling Unit (FWU) failure is a slippage condition which allows the Nf to exceed Nr with no usable torque transmitted to the MGB. This condition, usually caused by FWU bearing spit out, may be momentary (sometimes repeatedly) or permanent and may also result in breakup of the FWU. Slippage is indicated by any/all of the following symptoms:  Nf exceeding Nr torque dropping to zero, and a slight to moderate left yaw kick as the FWU slips. Sudden FWU reengagement causes a jolt in the airframe. If momentary slippage and reengagement occur too rapidly, symptoms may not be fully reflected in the cockpit quad tach and torque indicator; therefore, pilots should carefully monitor their instruments if FWU malfunction is suspected. In addition, a FWU may lock up following a momentary slippage, wherein the MGB can back drive the engine. This will be indicated by Nf not splitting off from Nr upon retarding the affected engine SCL to MIN GOV.

If a momentary slippage is indicated:

*1.     Collective — Maintain Nr.

*2.     Airspeed — As required (dual- or single-engine airspeed).

*3.     Pickle — External load as required.

*4.     Tanks — Jettison as required.

*5.     SCL — Affected engine to MIN GOV.

WARNING: If the No. 2 engine speed control lever is at or below MIN GOV and the Ng is less than 75 percent, hot exhaust gas may backflow into the engine compartment creating a fire hazard. Limit airspeed to less than 85 KIAS to reduce backflow. If a FWU slippage has occurred and dual-engine flight can be maintained, consideration should be given to securing the No. 2 engine. If a FWU lockup is suspected, maintain No. 2 engine at no less than 75 percent Ng to reduce possibility of backflow and to ensure engine lubrication.

Caution: In the event of a No. 1 or No. 3 FWU lockup, maintain the affected engine at or above ground idle to ensure lubrication of the power turbine shaft bearings.

6.     Land as soon as practical.

7.     Affected engine if locked up — Shut down last.

Permanent FWU slippage (in which the FWU slips without reengaging) is a form of power train failure. Refer to procedure for Failure in Helicopter Transmission System under Power Train Failure in this section.

12.23.10

Nose Gearbox Failure

Nose gearbox failure may be indicated by an abnormal noise or change in noise frequency.  A malfunction that would cause a binding or restriction within the gearbox will cause a high engine torque reading to be observed. A malfunction that would cause a no-load condition on the engine should produce a tendency for the engine to overspeed. If indications of nose gearbox failure are noted, do this:

*1.     Instruments and caution lights — Check.

*2.     Collective — Maintain Nr.

*3.     Airspeed — As required.

*4.     Pickle — External load as required.

*5.     Tanks — Jettison as required.

*6.     Speed control levers — As required (shut off affected engine, conditions permitting).

7.     Land as soon as practical.

12.23.10.1

Nose Gearbox Chip

Locator Light

When the CHIP DETECTED caution light is accompanied by either of the nose gearbox chip locator lights, check all other nose gearbox caution lights and gauges and engines torque meters to verify malfunction.

*1.     Instruments and caution lights — Check.

*2.     If malfunction verified or chip locator light does not extinguish — Perform Nose Gearbox Failure procedures.

3.     If chip locator light extinguishes, continue mission and closely monitor nose gearbox instruments and associated caution lights.

Note

An increase in torque for a given flight condition is a positive sign of nose gearbox internal binding or restriction.

12.23.10.2

Nose Gearbox Oil

System Failure

Loss of nose gearbox lubrication will be indicated by the nose gearbox oil temperature gauge and oil temperature and pressure caution lights. If indications of a nose gearbox oil system failure are noted, do this:

*1.     Instruments and caution lights — Check.

*2.     Perform Nose Gearbox Failure procedures.

12.23.11

Accessory Gearbox Failure

Accessory gearbox failure may be indicated by any abnormal noise.  If any abnormal noise is heard, check all instruments and electrically operated equipment for adverse indications. Systems that operate from the accessory gearbox may also give adverse indications. If indications of accessory gearbox failure are noted, do this:

1.     Instruments and caution lights — Check.

2.     Landing gear — Extend.

3.     Land as soon as possible.

12.23.11.1

Accessory Gearbox

Chip Locator Light

1.  Instruments and caution lights — Check.

2.  If malfunction verified or chip locator light does not extinguish — Land as soon as

possible.

3.  If chip locator light extinguishes — Continue mission and monitor closely.

Note

Accessory gearbox failure will result in the loss of second stage, utility, and engine start pumps, AFCS and other associated systems, and the No. 1 and No. 3 generators.

12.23.11.2

Accessory Gearbox

Oil System Failure

Loss of accessory gearbox lubrication will be indicated by the accessory gearbox oil temperature and pressure caution lights. If loss of accessory gearbox lubrication is indicated, do this:

1. Instruments and caution lights — Check.

2. Landing gear — Extend.

3. Land as soon as possible.

12.23.11.3

Main Gearbox to Accessory Gearbox Drive Shaft Failure

In the event of an in-flight accessory gearbox failure because of failure of the transmission to accessory gearbox drive shaft, it may be possible to regain lost systems by starting the APP. If loss of all AGB driven systems is indicated and malfunction was not preceded by loss of AGB oil pressure, nor accompanied by AGB chip light/abnormal noises, the AGB and its driven systems may be regained; do this:

*1.     APP — START.

*2.     Land as soon as possible.

Note

Failure of the main gearbox to accessory drive shaft will result in the loss of second stage, utility, engine start pumps, AFCS and associated systems, and the No. 1 and No. 3 generators.

12.23.12

Intermediate or Tail Gearbox Failure and Chip Light

Other than the chip light and the TGB/IGB OIL PRESS caution lights, there are no other instruments or caution lights with which to verify impending failures. A combination of chip light and corresponding OIL PRESS caution light confirms an impending failure. Additional flight indications of impending failure may include heading control difficulty, yaw kick, high frequency vibrations, and unusual or loud grinding noises from the tail section.

If impending failure is imminent as noted by combination of chip and corresponding OIL PRESS light, illumination of any caution light with additional flight indications discussed above, or any of the flight indications discussed above, proceed as follows:

*1.     Land immediately.

If only a single caution light illuminates without any additional indication of failure, proceed as follows:

1.     Land as soon as possible.

2.     If the caution light extinguishes — Continue flight and monitor closely.

3.     If caution returns — Land as soon as possible.

12.23.13

Windshield Failure

When a glass-covered windshield breaks, the entire surface crazes.  Visibility through the crazed windshield is severely limited. If the inner surface of a failed windshield remains intact:

1.     Reduce airspeed to 80 knots.

2.     Manually close EAPS doors.

3.     Land as soon as practical.

If a complete failure of the windshield occurs:

1.     Reduce airspeed as necessary for comfort within the cockpit.

2.     Manually close EAPS doors.

3.     Monitor engine instruments for indications of possible FOD.

4.     Land as soon as practical.

12.24

 LIGHTNING STRIKE

Lightning strike can occur while flying in the vicinity of thunderstorms. Damage to main and tail rotor blades in the form of arcing, erosion and heat annealing will result. Engineering analysis of blades subjected to an actual in-flight lightning strike concluded that the damage to the blades can be so severe that the fatigue life would be reduced to a few hours or even minutes. If a lightning strike is suspected, the helicopter should be landed and inspected. In past cases, major hidden damage was inflicted and was associated with minor appearing visible/external damage to the spot or pockets; however, no hidden damage was found without visible/external indications of some kind.

If lightning strike suspected:

*1.     Airspeed — 80 KIAS.

*2.     Land as soon as possible.

12.25

GROUND RESONANCE

Characteristics and the tendency for development of ground resonance are discussed in Chapter 11.  Immediate corrective action at the onset of ground resonance is imperative to prevent structural damage. Proceed as follows:

*1.     If able — Take off.

*2.     If unable to take off — Emergency shutdown.

12.26

OSCILLATIONS

Chapter 11 describes the aircraft flight characteristics, tendencies, and types of oscillations which are most likely to be encountered. If the conditions discussed in Chapter 11 are encountered, proceed as follows:

*1.     Flight control — Release.

If oscillations do not dampen within several seconds:

*2.     External cargo — Jettison.

12.27

 SUSPECTED ROTOR DAMPER FAILURE

When the rotor damper fails, an unbalanced rotor condition may be felt as a low-frequency beat or

lateral vibration.

Rotor blades will normally stay in track. If a rotor damper is suspected of failing, do this:

1.     Make small, smooth control inputs.

2.     Slowly increase main rotor rpm.

3.     Slowly reduce airspeed to 80 KIAS.

4.     Use small bank angles.

5.     Land as soon as practical. If vibrations become excessive.

6.     Land as soon as possible.

Note

A shallow approach to a running landing is preferable.  However, if conditions do not permit, then an approach to a touchdown (no hover) landing should be made.

7.     After helicopter has come to a stop, accomplish an engine shutdown without use of rotor brake.

WARNING

A rotor damper failure could lead to ground resonance.

12.32

EMERGENCY LANDING

Aircrew:

*1. Cabin occupants — NOTIFIED/SEATBELTS FASTENED.

*2. Lower personnel door, ramp/ramp door and external cargo hatches — CLOSED.

*3. Crew — Seat belts fastened/inertia reel locked (AFC−562).

WARNING

Failure to remove aircrewman safety belt (gunners belt), when simultaneously restrained by troop seat or crew chief seat safety harness (seat belt), may result in serious injury or death in the event of a hard or crash landing.

*4. Notify pilot that cargo/passengers/crew prepared for emergency landing.

12.34.4

Water Autorotative Landings

Autorotative landings on water differ from land, in that touchdown speed must be held to a minimum. The helicopter should enter the water with a near vertical descent if possible. Refer to Three-Engine Failure (Autorotative Landing) in this chapter.

*1.     Autorotate as described under Three-Engine Failure.

*2.     Enter water tail rotor first.