Dual Engine Failure

Gulfstream GVII

Eddie sez:

This procedure is fairly straight forward except for one thing: the need to turn both batteries off if both fuel low pressure warning CAS messages appear. Why? The AFM doesn't say. I asked several engineers at Gulfstream and was told that if the engines starve for fuel at high altitudes it could be that the fuel pumps "lost communications" with the BPCU and turning the batteries off and on will reset them. I've also been told that the problem may originate in the BPCU causing the problem to begin with. In either case, with no other electrical power connected to the air data probes, that will deprive the flight control computers with ADS information, putting them into alternate control law. Hence the need to do a Flight Control Reset.

Everything here is from the references shown below, with a few comments in an alternate color.

Last revision:

2020-07-20

AFM Procedure

The AFM writers have been practicing with a new concept in their abnormal and emergency procedures where the steps written in bold can be thought of as conditional. Treat the item as a question. If the answer is yes, complete the following steps. Otherwise, move on to the next numbered step.

[AFM, §04-06-30]

CAUTION

THE FADEC WILL NOT PREVENT A TGT EXCEEDANCE DURING AN AIRSTART.

Corrective Action

  1. Altitude . . . Begin immediate descent

  2. Airspeed . . . Maintain 285 KCAS / 0.9M

  3. Crew Oxygen Masks . . . Don

  4. MIC (COMM JACKS) . . . MASK

  5. If L-R Fuel Pressure Low (warning) CAS messages are displayed:
  6. CAUTION

    WITH MAIN BATTERY POWER OFF, DU1 AND DU4 WILL NOT BE AVAILABLE. REFERENCE SFD FOR AIRCRAFT CONTROL. FLIGHT CONTROLS WILL REVERT TO ALTERNATE MODE.

    1. MAIN BATTERIES (Left and Right) . . . OFF for 5 seconds, then ON
    2. FCS RESET . . . Select
    NOTE

    The UPS and EBHA batteries can power the flight controls for 30 minutes when APU, RAT, and engine mounted generators are not operating. APU or RAT power should be obtained as soon as practical.

  7. Above 37,000 feet:

    1. RAT . . . Deploy

    2. RAT GEN . . . Verify On

  8. At or below 37,000 feet:

    1. APU MASTER . . . ON
    2. CAUTION

      A MAXIMUM OF TWO APU START ATTEMPTS ARE RECOMMENDED. IF APU FAILS TO START, VERIFY FUEL PRESSURE BEFORE SECOND START ATTEMPT.

    3. APU . . . START

    4. APU GEN . . . Verify On

  9. If the APU is operating:

    1. RAT GEN . . . OFF

    2. Throttles (Left and Right) . . . IDLE

    3. FUEL CONTROLS (Left and Right) . . . OFF

    4. MAIN FUEL PUMP and ALT FUEL PUMP (Left and Right) . . . ON

    5. ENG BLEED AIR (Left and Right) . . . OFF

    6. ECS Packs (Left and Right) . . . OFF

    7. Engine to be Started First . . . Select

    8. Below 30,000 feet, perform APU Assisted Airstart

    9. (1) FUEL CONTROL (Selected Engine) . . . RUN

      (2) ENGINE START . . . PRESS

      (3) Engine Instruments . . . Monitor start

      (4) After the First Start Has Concluded

      (a) FUEL CONTROL (Other Engine) . . . RUN

      (b) ENGINE START . . . PRESS

      (c) Engine Instruments . . . Monitor start

      (5) If either start was successful:

      (a) Go to Step 12.

  10. If the APU fails to start:

    1. a. Altitude . . . Continue descent below 16,500 feet

    2. RAT . . . Deploy

    3. RAT GEN . . . Verify On

    4. Throttles (Left and Right) . . . IDLE

    5. FUEL CONTROLS (Left and Right) . . . OFF

    6. MAIN FUEL PUMP and ALT FUEL PUMP (Left and Right) . . . ON

    7. Below 16,500 feet, perform Windmill Airstart

    8. (1) Airspeed . . . 250 KCAS minimum

      (2) N2 . . . 9% minimum

      (3) FUEL CONTROLS (Left and Right) . . . RUN

      (4) Engine Instruments . . . Monitor start

      (5) If either start was successful:

      (a) Go to Step 12.

  11. If both engines fail to restart, continue restart attempts, (altitude permitting):

    1. a. FUEL CONTROL . . . OFF to RUN

    2. If APU air is available: (1) START BUTTON . . . PRESS

  12. If restarts remain unsuccessful:

    1. a. Refer to:

    2. 04-06-50, Dual Engine Out Landing Procedure, or

      04-19-20, Ditching.

  13. If one engine restarts:

    1. Refer to 04-08-20, Assisted Airstart.

  14. If both engines restart:

    1. ENG BLEED AIR (Left and Right) . . . ON

    2. ECS Packs (Left and Right) . . . ON

    3. YAW TRIM . . . Neutralize

    4. Airplane . . . Land as soon as possible


See Also:

Gulfstream GVII-G500 Airplane Flight Manual, Revision 4, August 29, 2019

Gulfstream GVII-G500 Production Aircraft Systems, Revision 3, July 15, 2019