B757 / B767 Simulator Prep

4.14 FCT 757/767 (TM)

Engine Inoperative Cruise/Driftdown

Engine Inoperative Cruise/Driftdown

Execution of a non-normal checklist or sudden engine failure may lead to the

requirement to perform an engine inoperative driftdown and diversion to an

alternate airport. Engine inoperative cruise information is available from the

FMC. An analysis of diversion airport options is available using the FMC ALTN

page (as installed).

If an engine failure occurs while at cruise altitude, it may be necessary to descend.

The autothrottle should be disconnected, thrust reference set to CON and the

thrust manually set to MCT on the operative engine. On the FMC ACT CRZ page,

select the ENG OUT. This displays MOD CRZ calculated on engine out MCT and

maintaining the airspeed displayed on the EO SPD line.

Set the engine out cruise altitude in the MCP altitude window and execute the

ENG OUT CRZ D/D page. The thrust reference mode on the EICAS display will

display CON. The airplane descends in VNAV using the VNAV SPD pitch mode.

Once the descent rate has decreased to 300 fpm during driftdown it is held

constant by the FMC until altitude capture.

At altitude capture the ENG OUT CRZ page is displayed. Maintain MCT on the

operative engine and driftdown altitude until the E/O SPD speed is established.

Maintain this speed using manual thrust adjustments.

After level off at the target altitude, maintain MCT and allow the airplane to

accelerate to the single engine long range cruise speed. Maintain this speed with

manual thrust adjustments. Entering the new cruise altitude and airspeed on the

ECON CRZ page updates the ETAs and Top of Descent predictions. When the

ENG OUT VNAV mode is selected and an engine-out condition is detected, the

FMC computes engine-out trip predictions, guidance parameters, and MAX ALT

consistent with the detected engine-out conditions, the selected thrust rating using

the actual bleeds. Refer to Engine Out Familiarization, chapter 7, for trim

techniques.

If required to cruise at maximum altitude, set MCT, establish a climb and

decelerate slowly to ENG OUT CRZ speed. At level off select ENG OUT LRC

for best fuel economy.

An alternate target driftdown speed can be selected using the MOD CRZ or ENG

OUT D/D page. LRC speed would result in a lower driftdown altitude but better

fuel performance. A company specified speed could be selected and provides for

a higher driftdown speed and a shorter flight time to the alternate.

An ENG OUT ALT can be entered on the MOD CRZ or ENG OUT D/D page. If

an engine out cruise altitude lower than the computed maximum altitude is

entered, the FMC commands a cruise descent at approximately 1250 fpm rather

than a driftdown schedule.

Unless altered by the pilot, the level off cruise mode will be the same as was used

during driftdown. FMC fuel and ETA calculations for driftdown and the

remainder of the trip will be consistent with the selected speed mode. For best fuel

performance select the engine-out LRC mode following a minimum drag speed

(E/O) driftdown.

When VNAV is not used during engine out, set MCT on the operative engine and

maintain altitude until the airplane decelerates to the displayed appropriate engine

out speed. Use engine out speed from the FMC while descending to the engine out

cruise altitude. Remain at MCT until the airplane accelerates to LRC, then

maintain LRC speed with manual thrust adjustments. If the FMC is inoperative

use turbulence penetration airspeed to driftdown and the engine out long-range cruise tables in the QRH.