C4202 "Fam 10"

Last updated: 3 June, 2008 16:46 by Bryan Weatherup
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The brief will begin with a procedural check with emphasis on Course Rules, Communications, and IFF

Loss of useful power (either a rollback or compressor stall): Engine malfunctions may result in a loss of useful power where the power available is insufficient to prevent the high rates of descent associated with low power/low propeller blade pitch situations. To determine whether or not the propeller should be feathered, check the VSI while descending at 100 KIAS clean. A descent rate in excess of 600-800 fpm will require the propeller to be feathered. The best glide performance power setting at 100 KIAS, aircraft clean, is 205 ft-lbs.

Fuel control rollback
Prop RPM
80-100 PPH

Reduced fuel flow (rollback) is typical of a fuel control unit pneumatic sensing system malfunction. If engine will not respond to PCL movements and ITT and N1 indicate the engine is running at a very low power settings, advance the EPL in an attempt to regain control of engine power by use of the manual fuel control system. N1 40-62% - indicating a "rollback" (fuel control unit stuck at minimum flow), proceed as follows:

  1. Condition lever - FULL INCREASE RPM

    NOTE - When using EPL maintain N1 above 65% to improve engine response and ensure generator stays online.

    If the resultant power available is insufficient to execute a PEL:
  4. ENGINE FAILURE procedure - EXECUTE.

    WARNING - When the engine is so underpowered that high rates of descent occur, any delay in feathering the propeller may result in insufficient altitude to reach a suitable landing site. It is not recommended to delay feathering the prop in the landing configuration below landing pattern altitude.

    If sufficient power is restored:
  5. PCL - IDLE

    CAUTION - Use of BETA is not recommended when performing a landing using the manual fuel control system. If the use of BETA is required, ensure the EPL is in the IDLE range or DISCONNECT before selecting BETA with the PCL.

Compressor stall - Compressor stalls may be characterized by an audible change in engine noise (a loud bang or backfire) with fluctuations in torque, ITT, N1, and fuel flow. Additionally, flames and smoke may be visible from the engine exhaust stacks. A severe compressor stall may result in engine damage and/or flameout. Compressor stalls may be caused by damaged or degraded compressor or turbine blades, disrupted airflow, or compressor bleed valve malfunction. If compressor stalls occur, proceed as follows:

  2. Cockpit environmental control - FULL FORWARD

    WARNING - Avoid unnecessary PCL movement. Advancing the PCL may result in further compressor stalls and engine flameout. Retarding the PCL further may limit maximum power available.

    If sufficient power is available:

    If sufficient power is insufficient to execute a PEL:
  5. Proceed to the nearest suitable landing field and execute the
  6. ENGINE FAILURE procedure.

    WARNING - Use of manual fuel control will only aggravate compressor stalls and could lead to flameout.

    WARNING - When the engine is so underpowered that high rates of descent occur, any delay in feathering the propeller may result in insufficient altitude to reach a suitable landing site.

    NOTE - If the situation permits, record the altimeter, OAT, max ITT, and duration of compressor stall.

    NOTE - If resultant power is sufficient to maintain a rate of descent less than the feathered condition (600-800 fpm clean), consideration should be given to allowing the engine to operate until the field is made.

Emergency power lever (EPL) - The manual fuel control system consists of a cockpit control which provides the pilot with direct mechanical linkage to the bellows and the fuel metering pin in the FCU. The manual fuel system is a backup system only and is used in the event of a malfunction in the pneumatic section of the FCU.

When engaged, the system will bypass all pneumatic failure modes which result in minimum fuel flow and/or lack of engine response to PCL movement. Movement of the emergency power lever (EPL) toward max, mechanically depresses the bellows to schedule more fuel to the engine. This system relies on torque tube pretension to reduce power as the EPL is moved toward the idle range. When using the EPL, normal operation of the landing gear warning system is provided.

If loss of power occurs due to a malfunction of the FCU, power may be restored using the EPL. No automatic fuel scheduling is incorporated, and fuel metered to the engine is a direct function of the lever position. Idle RPM, when required, should be maintained above 65% N1 by the pilot to eliminate the lack of EPL response in the idle range, and improve engine response. The manual fuel control system bypasses the protective devices relying on pneumatic bleed air as the operational parameter for the fuel topping function of the primary governor. Failure of the FCU at high power cannot be corrected with the EPL.

NOTE - With gear up, normal operation of the gear warning system occurs when the PCL and the EPL are retarded below 75% N1. Additionally, the warning system will activate (with gear up) when both the PCL and EPL are forward of the 75% switch.

CAUTION - Compressor stall, vibrations and overtemp are probable with rapid accelerations of the EPL, particularly at the low-end of the power spectrum.

CAUTION - During an actual rollback, if power is restored with the EPL, exercise caution not to excessively reduce power in the final landing transition, as sink rate will drastically increase at low power.

  1. EPL activation:
    1. Condition lever - FULL INCREASE
    2. EPL - Out of detent; slowly advance to desired power setting.
    3. PCL - IDLE
  2. EPL Normal Use - Utilize smoothly in the same manner as the PCL with considerations/limitations as set forth above. The use of the EPL will only be practiced at altitude. It will NOT be used for training purposes in either the normal or emergency landing patterns.
  3. EPL deactivation:
    1. PCL - advance to power setting above EPL

Common errors:

1) Failure to check condition lever at full increase.
2) Failure to operate the EPL smoothly on activation.
3) Failure to monitor power settings during changes in altitude.
4) Using the PCL for operation of the manual fuel system after EPL is engaged.

Primary governor failure

Normally, the primary and overspeed governor and fuel topping function will act in sequence to hold propeller rpm within suitable range to continue flight or to reach a suitable repair facility. If the propeller is being governed by the fuel topping governor alone, expect moderate surges in propeller rpm, N1, torque and fuel flow as fuel topping activates and deactivates.

Propeller Speed Above 2200-2332 RPM / 2332+ RPM
1. Attempt to adjust rpm to normal operating range by manipulation of the Condition Lever.
If normal indication is restored
2. CONTINUE FLIGHT / Land ASAP using NORMAL procedures (if 2332+ RPM)
If adjustment of the Condition Lever fails to produce normal propeller response
3. Land ASAP using PEL procedures.

CAUTION - Advancing the EPL beyond the point at which the fluctuations are minimized will aggravate the overspeed condition.

NOTE - If activation of the primary fuel topping governor has occurred, Py air will be bled automatically and fuel flow will be reduced towards minimum, causing corresponding fluctuations in N1, torque, fuel flow, and prop rpm as rpm surges to 2398 and is then reduced again by the fuel topping function. Engaging the EPL will lessen the severity of low-end fluctuations.

Uncommanded Propeller Feathers

  1. Condition lever - FULL INCREASE RPM
    If propeller remains feathered:
  2. PCL - ADVANCE (as required)
    If the resultant power does not improve performance:
  3. PCL - IDLE
  4. Execute ENGINE FAILURE procedures.

NOTE - In the event of a primary governor shaft failure, the propeller will move toward feather; however, unboosted engine oil pressure alone may be sufficient to maintain propeller pitch between feather and normal governing rpm range at high-power settings. Resultant power may be sufficient to maintain level flight.

NOTE - Because it is feasible for the propeller to unfeather and restore useful power, consideration should be given to leaving the condition lever at FULL INCREASE RPM until intercepting the emergency landing pattern (ELP).

NOTE - Generator power will not be available after engine shutdown.

Propeller RPM fluctuations
Propeller rpm fluctuations caused by fluctuating blade angle will be accompanied by a corresponding torque flux and will be audible. Propeller rpm fluctuations may be caused by a faulty propeller overspeed governor test circuit or a malfunctioning primary governor. A malfunctioning primary governor may be caused by metal particles in the oil system and may therefore be the precursor to a chip light.

  1. PROP TEST circuit breaker - PULL
    If fluctuations cease, continue flight. If fluctuations continue:
  2. Land ASAP using PEL procedures.

New Maneuvers for this event:

Use of the EPL (see discussion items)

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