Max Power Assurance Runs For Cf65 0 C2

[napoleon]

Can anyone tell me the significance of the MPA runs and what can be assumed from them?

[IFixPlanes]

MPA in conjunction with CF6-50-C2 or MPA generally?

[napoleon]

IFixPlanes
Hi there to these engines in particular and when fitted to A300 B4-200

[IFixPlanes]

Sorry, but i have no licence on the B4

[gas path]

Max power assurance runs are exactly that. It is used after an engine change for instance, IIRC there were two targets 50% and 75% the idea being to 'shoot' for a particular N1 based on temperature and field elevation, the resulting figures for thrust lever angle/ N2/ Fuel flow/ EGT had to be below the figures as set out in the manual. This then guaranteed that a max. power takeoff was achievable without exceeding any limits.

[Clarence Oveur]

From the A300B4 AMM:

Power Assurance Check

(a)General

This procedure is used as a functional test to determine the
capability of the engine to produce required Takeoff Power without
exceeding EGT and N2 limits during use of Full Rate Power in a Hot
Day environment (Above Flat Rate Outside Air Temperature).

NOTE: MPA is an effective tool for engine performance evaluation by an operator,
but should not be used solely to constitute the acceptance or rejection of an engine.

NOTE: This check is desired when engine maintenance action has
occurred that may have impacted engine operation. This check
can best be used to detect large changes in margin by
comparisons to previous power assurance runs, to confirm the
likelihood of acceptable margins, or to evaluate flight crew
concerns.

NOTE : Because of instability normally encountered during a power
assurance run, other quality check procedures may provide a
more accurate assessment of margin. Those other quality checks
include a test stand run per the Engine Manual, and/or review
of flight data acquired during takeoff and processed using OEM
provided algorithms.

[napoleon]

OK lets assume an engine has a margin of 8 degrees C on a 20 degree C day. Would that engine produce take off power at say 40 degrees C

[barit1]

If the PA is properly done and calculated, then 8° margin is 8° margin at any hot day point (i.e. above the TO flat rated temp.)

[napoleon]

Sorry meant to say "OK lets assume an engine has a margin of 8 degrees C on a 20 degree C day. Would that engine produce take off power at say 40 degrees C without exceeding the Max EGT

[barit1]

Yes it should, although as the MPA notes declare, there is some instability/uncertainty in the MPA, and there are more precise ways to pin down the performance data on an engine (cruise trend data, or a test cell run). The MPA is just the quickest & cheapest method; Nothing wrong with it if you recognize its limitations.

[napoleon]

Thanks a lot. I have gathered that infact the only way to "prove" an engine is to observe take off power on the take off run. Yes or no?

[barit1]

Of course the only "real" test is TO, but these are the "predictors" in probable order of increasing precision:

1) PA (including MPA)
2) Test cell
2) cruise trend monitoring