B737 Classics. Reverse thrust timing on standby hydraulic system
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B737 Classics. Reverse thrust timing on standby hydraulic system
Question on the operation of the B737-300 Thrust Reverser using the standby hydraulic system. The FCOM states: “When the standby system is used, the affected thrust reverser deploys and retracts at a slower rate, and some thrust asymmetry can be anticipated”
The term “slower rate” is difficult to quantify in terms of seconds. Tests in one B737-300 flight simulator reveals it takes approximately 10 seconds for the interlocks to fully open from first movement of the reverse thrust levers and another seven seconds to accelerate the N1 from 22% ground idle to 88% maximum reverse with 20K engines. That is an approximate total time lapse of 17 seconds from first movement of reverse thrust levers until maximum reverse N1 is obtained. Does anyone know if these figures accurately reflect the real aircraft?.
On a B737-400 simulator with 22K engines, there was no discernible difference in rate of thrust reverser operation between the standby hydraulic system and normal hydraulic system operation. Both operated very quickly (about 3 seconds to get through the interlocks). Same noted in a Boeing 737 NG simulator.
Request opinions on how many seconds from the first lifting of the reverse thrust levers to the interlock then to full reverse, should be achieved under standby hydraulic system. Also, is there any difference in time to full reverse thrust if both thrust reversers are used simultaneously as in a manual reversion landing, as against a single reverser operation on the standby system?
The term “slower rate” is difficult to quantify in terms of seconds. Tests in one B737-300 flight simulator reveals it takes approximately 10 seconds for the interlocks to fully open from first movement of the reverse thrust levers and another seven seconds to accelerate the N1 from 22% ground idle to 88% maximum reverse with 20K engines. That is an approximate total time lapse of 17 seconds from first movement of reverse thrust levers until maximum reverse N1 is obtained. Does anyone know if these figures accurately reflect the real aircraft?.
On a B737-400 simulator with 22K engines, there was no discernible difference in rate of thrust reverser operation between the standby hydraulic system and normal hydraulic system operation. Both operated very quickly (about 3 seconds to get through the interlocks). Same noted in a Boeing 737 NG simulator.
Request opinions on how many seconds from the first lifting of the reverse thrust levers to the interlock then to full reverse, should be achieved under standby hydraulic system. Also, is there any difference in time to full reverse thrust if both thrust reversers are used simultaneously as in a manual reversion landing, as against a single reverser operation on the standby system?
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The time for the T/R sleeves to translate open using standby hydraulics is required to be 5 seconds or less. Stowing has to be 8 seconds or less. This compares with 3 to open and 5 seconds to retract during normal ops. These times are for one eng. at a time as they are part of a maintenance test procedure.
