PPRuNe Forums - Max Motoring

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greenslopes

7th Jul 2006 01:04

Max Motoring

The B 737 NG manuals for pilots seems to have removed the exact definition of max motoring. It mentions that it should be used but doesn't say what it is. From memory on the classics 2% N1 acceleration over five Seconds. Does any LAME have a definition and a reference?
Many Thanks

WJman

7th Jul 2006 01:55

As far as I've ever known max motoring is as high an N2 you can get. When N2 stabilizes and is no longer rising then you are at max motoring.
I have seen many diffrent max motor levels on the same aircraft type with the same engines. It all depends on engine condition,age, windspeed and other variables.
I don't know if there is an exact number but it would be hard to keep constant, and would be a pain for us engineers to diagnose a snag that was written up as "did not reach max motoring".
Hope this helps.

IFixPlanes

7th Jul 2006 22:23

Here is a Copy out of the AMM (Aircraft Maintenance Manual ):

Quote:

Start the Engine Procedure (Normal Start)
...
...
When the engine is at 25% N2 or the maximum motoring speed, move the start lever to the IDLE position.
If the engine speed is less than 25% N2, you can move the start lever forward to the IDLE position when the engine is at its maximum motoring speed.
NOTE:
The maximum motoring speed is defined as the speed when the rate of increase in N2 is less than 1% during a 5 seconds time period. The minimum maximum motoring speed is 20% N2.
...

HIH;)

Capt Chambo

8th Jul 2006 03:53

Quote:

Originally Posted by greenslopes

Not an engineer, just a pilot, but looking through my manuals for both the classic, and the NG the definition of "Max Motoring" is only quoted in the Part B Procedures section (JAR Speak) or the Flying Manual from pre-JAR days.
In both cases it is defined as "....... N2 acceleration is less than 1% in approximately 5 seconds".
Your Ozzie pilots will have a similar manual and it is in the section Normal Procedures>Start procedures.
Hope that helps.

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