a. Main drive shaft failure
b. Engine restart in flight
c. Vibration identification
d. Mast bumping
e. Ditching

INTRODUCE

a. Engine overspeed (Nf) Rotor RPM (Nr)
b. Underspeeding Nf or Ng (Low Nr)
c. Compressor stall
d. Engine failure
e. Engine restart
f. Electrical fire
g. Main drive shaft failure

PRACTICE

a. All FAM stage checklists and voice reports
b. Normal starting/shutdown procedures
c. Abnormal starts
d. Generator/electrical malfunctions
e. Hydraulic system failure
f. Chip light
g. Post shutdown fire/internal

DISCUSS

a. Main drive shaft failure - The main drive shaft, also known as the barbell shaft, connects the engine to the transmission. It has a flexible splined coupling on each end, giving it its name. The aft end is connected to the freewheeling unit. Then the shaft passes through the firewall and connects to the transmission input pinion. Failure of this shaft would unload the freewheeling compressor and leave the rotor transmission, and consequently, the rotor, underpowered. [Systems 4-6]

b. Engine restart in flight - An engine restart in flight would most likely result from a malfunction of the fuel control unit or fuel system. The decision to attempt an engine restart during flight is the pilot's responsibility and is dependent upon the pilot's experience and the operating altitude. Consideration must be given to the cause of the failure prior to attempting restart. Engine Restart [NATOPS 14.5] included below.

c. Vibration identification - It is important to note that sources of vibrations can only be from rotating or moving parts.

    Low frequency vibrations - Classified as one or two beats per revolution. Most commonly caused by the main rotor. Vertical "One per" is caused by an out-of-track condition, which causes more lift on one blade than another at the same point of rotation. Lateral "One per" vibrations are caused by a difference in weights of blades (spanwise imbalance) or a misalignment of blades (chordwise imbalance). Two-to one vibrations are inherent in two-blades systems at about 100 to 110 kts.
    Medium frequency vibrations - Classified as 4 to 6 beats per revolution, they are also inherent in helicopters. If there is an increase, it may be because of a change in aircraft's ability to absorb noise, or a loose part vibrating with rotor system.
    High frequency vibrations - Felt as a "buzz" due to high speed. Always present as well, it is caused by anything that vibrates at a speed higher than that of the tail rotor. Common problems are tail rotor out-of-track, out-of-balance, or worn tail rotor components. [NATOPS 11-9, AERO 5-12]

The most influential causes are
            1) Low G maneuvers (below 0.5 g's)
            2) Rapid, large cyclic movements (especially forward)
            3) Flight near longitudinal/later CG limits
            4) High slope landings.
            Less influential causes are max sideward/rearward flight, sideslip and blade stall.

Warning - Should mast bumping occur in flight, catastrophic results are probable. Since conditions causing rotor flapping are cumulative, improper pilot response/recovery techniques to flight situation approaching or favorable to mast bumping can aggravate the situation and lead to in-flight mast bumping and mast separation. [NATOPS 11.5]

Low G flight, such as crossing a ridgeline, masking and unmasking, acquiring/staying on a target, and recovery from a pull-up, allows thrust to be unloaded from the rotor head. Incorrect pilot inputs for engine failure and tail rotor failure can also lead to excessive flapping. Recover should be made by reapplying thrust to the rotor head again, usually through aft cyclic. [System 5-11]
 
 
 

CONDITION  Start/Shutdown..........................  Rear/Side flight...........................    Slope Landing...........................    Engine failure at high forward airspeed        Low G maneuvers.......................   (below +0.5 G)   (Other than nose high)      Nose high, low airspeed...........

RECOVERY TECHNIQUE [NATOPS 11.6]  Cyclic: Move to stop bumping  Cyclic: Move slightly toward center  Pedal: Align nose w/ direction of travel  Cyclic: Move toward center to stop bumping; reestablish hover    Cyclic: Move aft to maintain positive G (positive thrust), retain Nr, and avoid mast bumping during auto entry  Collective: As req. to maintain Nr    Cyclic: Aft, then center laterally to regain positive g (positive thrust) on rotor and maintain Nr  Collective: Judiciously increase, if possible  Pedal: As req.    Cyclic: Neutral

 

MAST BUMPING [NATOPS 14.11]

    INDICATIONS:
            Sharp two-rev knocking

    PROCEDURES:
       During high speed sideward or rearward flight:
            *1. Cyclic Immediately Apply Smoothly Toward Center
            *2. Pedals Immediately Apply as Req. to Align the Nose with the Direction of Travel
         *3. Land immediately

       During other flight conditions:
            *1. Cyclic Immediately Apply Aft to Establish Positive G Load on Rotor, Then Center Laterally
            *2. Controls As Req. to Regain Balanced Flight
            *3. Land immediately
 

e. Ditching
DITCHING - POWER ON [NATOPS 16.3.4.1]

Once the decision has been to made to ditch:

            1. Passengers and crew Alert
            2. Shoulder harness Locked
            3. Mayday/IFF Transmit/EMER
            4. Perform a normal approach to 3 to 5 feet hover
            5. Doors Jettison
            6. Nonessential personnel Execute Emergency Egress
            7. Helicopter Move, Safe Distance Away
            8. Vertical landing Perform
            9. Twist grip Close
            10. Collective Increase Slowly to Maximum Pitch
            11. Cyclic Maintain Helicopter Upright As Long As Possible
            12. Emergency Egress Execute
            13. Lifevest Inflate (when well clear of helicopter)

DITCHING - POWER OFF [NATOPS 16.3.4.2]

        Time permitting:
            *1. Autorotate
            *2. Shoulder harness Locked
 
        If time and altitude permits:
            *3. Crew/passengers Alert
            *4. Mayday Transmit On Guard
            *5. Squawk EMER
            *6. Doors Jettison

Warning - Do not abandon helicopter until rotor blades have stopped. Do not inflate lifevest until well clear of the helo.

            *7. Underwater egress Execute
 

INTRODUCE:

a. Engine overspeed (Nf) Rotor RPM (Nr)
ENGINE OVERSPEED (Nf) ROTOR RPM (Nr) [NATOPS 14.6]

        INDICATIONS
                Nr increase
                Nf increase
                Ng increase
                TOT increase
                Right yaw
                Engine noise increase

        PROCEDURES:
                *1. Collective Increase (to maintain Nr in operating range)
                *2. Twist grip Reduce (to maintain Nf in operating range)
                *3. Collective/twist grip Readjust
                *4. Land as soon as possible

Note - The Nf overspeed must be continually controlled by coordinating collective and twist grip.
 

b. Underspeeding Nf or Ng (Low Nr)
UNDERSPEEDING Nf/Nr [NATOPS 14.7]

If Nr can be maintained at 90% or higher in level flight, it is safe to proceed to a suitable landing site. Terrain permitting, a sliding landing offers the lowest power required. Do not decelerate below the minimum airspeed of 50 KIAS while executing the power check. If some usable power exists but level flight cannot be maintained, that power, if sufficient, may be utilized to effect a landing or minimize rate of descent en route to a more suitable site for autorotation.
 
        INDICATIONS:
                Low Nr
                Low Nf
 
        PROCEDURES:
                *1. Collective Adjust to maintain Nr within limits
                *2. Twist grip Full Open
                *3. GOV RPM Full Increase
                *4. Check power available with Nr in limits
 
            If power is not sufficient:
                *5. Autorotate
 
            If sufficient power is available:
                 *6. Land as soon as possible
 

c. Compressor stall
COMPRESSOR STALL [NATOPS 14.9]

        INDICATIONS:
                Popping or rumbling noise
                Vibrations
                Rapid rise in TOT
                Ng fluctuation
                Loss of power
 
        PROCEDURES:
                *1. Collective Reduce (maintain Nr within limits)
            *2. Reduce severity of maneuver

            If TOT within limits:
                *3. Land as soon as possible
         If TOT not within limits:
                *4. Twist grip Reduce to maintain TOT within limits
                *5. Check power available with Nr within limits

            If power is not sufficient:
                *6. Autorotate
 
            If sufficient power is available:
                *7. Land as soon as possible
 
Warning - Be prepared for a complete power loss.

Warning - When accelerating the rotor system during the initial rotor engagement or after a full autorotation, exceeding 40% torque may induce compressor stall or engine chugging.

Note - Slight power (collective) reduction will often eliminate compressor stalls.

Note - Mild compressor stalls may occur that will allow powered flight if TOT is within limits.
 
 
d. Engine failure
ENGINE FAILURE [Adapted NATOPS 14.1]

Immediately upon engine failure, rotor rpm will decay and the nose will swing to the left, because of loss of power and torque. Except when near surface, it is mandatory that autorotation be established by immediately lowering the collective pitch to minimum. Right pedal decreases tail rotor thrust. High gross weights, increased g loads, and higher altitudes and temperatures will cause increased rpm, which other than that specified for maximum glide {94-95%}, will cause increased rates of descent. At 75 to 100 feet, a cyclic flare should be established to reduce airspeed, rate of descent, and increase rotor rpm. Caution should exercised to avoid striking tail; level skids before ground contact.
 
Note - The best glide airspeed is 72 KIAS. The minimum rate of descent airspeed is 50 KIAS. Do not exceed 100 KIAS in sustained autorotation.

Note - If time and altitude permit, engine restart may be attempted. The decision to attempt a restart is the pilot's responsibility and is dependent upon the pilot's experience and operating attitude.

Note - All autorotative landings should be made into the wind at a suitable landing site.
 
            INDICATIONS:
                    Nr decrease
                    Rapid settling
                    Left yaw
                    Low rotor rpm caution light and audio
                    Engine-out caution light and audio
 
ENGINE FAILURE AT HIGH AIRSPEED AND LOW ALTITUDE [NATOPS 14.1.1]
Should an engine failure occur at high airspeed and low altitude, a rapid loss of Nr accompanied by a severe nose-tucking tendency will occur.
 
            PROCEDURES:
                    *1. Cyclic Immediately Apply Aft
                    *2. Autorotate

Warning - Rapid cyclic movement should be avoided to preclude mast bumping.
 
ENGINE FAILURE IN FLIGHT [NATOPS 14.1.2]
In the event of an engine failure in flight, a safe landing can be accomplished, provided that altitude and airspeed combination is within safe limits and altitude is sufficient to permit selection of a suitable landing area.

            PROCEDURES:
                    *1. Autorotate
                    *2. Shoulder harness Locked

                If time and altitude permit:
                    3. Crew/passengers Alert
                    4. Mayday Transmit on Guard
                    5. Squawk EMER
 

e. Engine restart
ENGINE RESTART IN FLIGHT [NATOPS 14.5]

An engine restart in flight would most likely result from a malfunction of the fuel control unit or fuel system. The decision to attempt an engine restart during flight is the pilot's responsibility and is dependent upon the pilot's experience and the operating altitude. Consideration must be given to the cause of the failure prior to attempting restart.
 
If attempting a restart, proceed as follows:

            PROCEDURES:
                    *1. Autorotate
                    *2. Fuel valve Check On
                    *3. Starter Engage
 
                If light off occurs:
                    *4. Land as soon as possible
 
Caution - If Ng is allowed to fall below a minimum of 15% Ng the close the twist grip and perform a normal start.

Note - Ng will not decrease below minimum starting speed within 10 seconds because of rotational inertia plus possible ram effect. The twist grip can be left in the full open position since fuel flow during the start will be on the normal acceleration schedule.
 
Caution - Do not attempt to start above 12,000 feet as TOT rises too fast to control.
 

f. Electrical fire
ELECTRICAL FIRE [NATOPS 4.16]

            INDICATIONS:
                    Loadmeter shows excessive load
                    DC voltmeter shows excessive load
                    Smoke
                    Fumes
                    Sparks
 
            PROCEDURES:
                    Prior to shutting off all electrical power, the pilot must consider the equipment that is essential to the particular flight environment that will be encountered (e.g., flight instruments and fuel boost pumps).
 
ELECTRICAL FIRE UNKNOWN ORIGIN [NATOPS 14.16.1]

            PROCEDURES:
                    *1. BAT switch OFF
                 ©*2. STANDBY GEN switch OFF
                 ©*3. STBY ATT ID switch OFF if in VFR Conditions
                    *4. MAIN GEN switch OFF
                If fire persists:
                    *5. Land immediately
                If fire extinguishes:
                    *6. Land as soon as possible

 If the electrical power is required to restore minimum required equipment for continued flight, proceed as follows:
                    7. All circuit breakers Out
                 ©8. Check BAT RELAY CB In
                    9. BAT switch ON
                    10. MAIN GEN FIELD and MAIN GEN CB In
                    11. MAIN GEN switch Reset, then ON
                 ©12. STBY GEN switch ON
                 ©13. STBY IND ATT switch ON
                    14. Circuit breakers for essential equipment In One at a Time in Order of Importance
 
Note - Ensure corresponding bus supply circuit breakers are in to provide power to desired electrical equipment.

Note - Voltmeter will not indicate battery voltage until battery bus supply and voltmeter circuit breakers are in.

Note - Flight operation can be maintained without battery and generator. Instruments powered by the 28V DC power system, however, will be inoperable.
 
ELECTRICAL FIRE KNOW ORIGIN [NATOPS 14.16.2]

            PROCEDURES:
                    *1. Affected equipment Secure
                    *2. Affected C/B's Pull
                If fire persists:
                    *3. Electrical Fire Unknown Origin Proc. Execute
            If fire extinguishes:
                    *4. Land as soon as practicable {Because cause of fire known and extinguished}
 

g. Main drive shaft failure
MAIN DRIVE SHAFT FAILURE (BARBELL SHAFT FAILURE) [NATOPS 14.2]

            INDICATIONS:
                    Nr decrease
                    Nf/Ng rpm increase
                    Left yaw
                    Loud bang/noise

            PROCEDURES:
                    *1. Autorotate
                    *2. Twist grip Adjust to maintain Nf/Ng in operating range
                When on deck:
                    *3. Emergency shutdown Complete

Warning - The engine must continue to operate to provide tail rotor drive. Tail rotor drive effectiveness may be lost if Nf is allowed to go below 80%.
 

PRACTICE:
 
a. All FAM stage checklists and voice reports - CPT1
b. Normal starting/shutdown procedures - CPT1
c. Abnormal starts - CPT1
d. Generator/electrical malfunctions - CPT3
e. Hydraulic system failure - CPT3
f. Chip light - CPT3
g. Post shutdown fire/internal - CPT1