High Elevation Airport Operations

Gulfstream G450

Eddie sez:

The High Elevation Airport Engine Start checklists in the AFM (G450 Airplane Flight Manual, ¶02-08-70) and QRH (G450 Quick Reference Handbook, page NG-37) are misleading. They say "perform a normal right engine start as follows" and then leave out much of the checklist. You are expected to jump between the Normal Engine Ground Start Checklist and the one presented. I've added the normal steps below.

There are things you need to do when landing at a high elevation airport but the pressurization system takes care of itself as long as you are in AUTO mode and the FADEC adjusts automatically for the engines and generators. You will have a few extra steps on engine start but the checklist leads you through it. Aircraft with ASC 068 and aircraft after SN 4221 have a high altitude switch to consider. See G450 QRH NG-36 for the complete list of considerations with this switch.

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

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High Elevation Airport Operations

High Elevation Airports

[G450 Airplane Flight Manual, §02-08-70]

  • Use of oxygen by the flight crew while performing high-workload tasks at high elevation airports or at field elevations for which the flight crew is not acclimated is highly recommended.
  • Make sure you are in 100%.

  • Engine Start
    • The following topics contain recommended changes to the engine starting procedures to high elevation airports. During use of these procedures, the flight crew shall be alert to higher-than-normal TGT indications or the possibility of a hot start.
    • If engine Maintenance LTD message and an Engine ALT Control message are displayed and not associated with an EEC / P30 (A) (B) fault, then cycle the Fuel Control ON for three (3) seconds and OFF. If the messages clear continue normal operation. If the Engine Maintenance LTD message does not clear record for maintenance. If the Engine ALT Control message does not clear, attempt to return to EPR mode by selection on the Display Controller. If unable to return to EPR mode, maintenance is required prior to dispatch.
    • Perform a NORMAL Right Engine Start as Follows:
    • Much of the normal engine ground start checklist is missing from this procedure. The missing items appear in blue.

        BCN . . . ON

        PARK/EMERG BRAKE / PRESSURE . . . SET / 3000 PSI

        Power Levers . . . IDLE

        GUST LOCK . . . OFF

        ENGINE BLEED AIR . . . OFF

      1. Select the PWR XFR UNIT OFF/ARM switch to OFF to reduce load on the engine during start.
      2. Select one (1) MAIN or ALT (fuel boost) PUMP to ON. Ensure the remaining three (3) are OFF.
      3. Select the Crossflow Valve (X FLOW) to OPEN.
      4. ENGINE CONTROL . . . EPR Mode

        Engine Start 1/6 System Page . . . SELECTED

        Bleed Air Pressure . . . Check 28 PSI Minimum

        Note: Check that residual TGT is less than 200°C.

      5. Select the START MASTER switch to ON.
      6. Depress the R ENG START switch. The SVO icon will appear on the engine instruments display.
      7. At maximum motoring RPM, select the R FUEL CONTROL to RUN. The IGN icon will appear on the engine instruments display.
      8. Fuel Flow / TGT . . . MONITOR

      9. Verify SVO and IGN icons are extinguished at approximately 45% HP RPM.
      10. EVM . . . Check

      11. Verify right engine oil pressure is 17 psi.
      12. Verify Right Hydraulic System (R SYS) pressure is 3000 (±300) psi.
      13. When engine has stabilized at idle, select PWR XFR UNIT (PTU) OFF/ARM switch to ARM.
      14. Verify PTU hydraulic pressure is 3000 (+300 / -400) psi.
      15. Verify Single Rudder advisory CAS message is displayed.
      16. Verify engine idle is established at a minimum of 49% HP RPM. Due to FADEC compensation for altitude, actual idle speed indication may be higher.
    • Perform a NORMAL Left Engine Start as Follows:
      1. Perform Steps E through H of RIGHT ENGINE START, substituting the left engine for the right engine (L vs R).
      2. They mean steps 5 through 8

      3. Check Left Hydraulic System (L SYS), R SYS and PTU hydraulic pressures.
      4. Verify Single Rudder advisory CAS message is no longer displayed.
      5. Select R MAIN and L MAIN BOOST PUMPS to ON.
      6. Select the Crossflow Valve (X FLOW) to CLOSED.
      7. Select the START MASTER switch to OFF.
  • Taxi:
    1. FADEC will compensate for altitude, keeping ground idle speeds within limits. Thus the Left and Right Generators (L GEN / R GEN) will remain on line.
    2. Ensure that PASSENGER OXYGEN control panel is selected AUTO prior to takeoff.
  • Takeoff:
    1. Certain high elevation airports have preferential runways to takeoff and landing, i.e., upslope for landing and downslope for takeoff. Slope, headwind and tailwind conditions should be given due consideration.
    2. While holding brakes ON, advance power to RATED TAKEOFF EPR, then release brakes for takeoff.
    3. Expect slower-than-normal acceleration to 60 knots.

See Also:

Gulfstream G450 Airplane Flight Manual, Revision 35, April 18, 2013