Engine/APU component test???

[AeroTech]

Hi,

In a modern or recent jet engines/APUs and after replacement of SMALL engine /APU components or accessories like N1 and/or N2 speed sensors, temperature sensors (oil….), or pressure sensors…etc (not fuel or hydraulic pump,…); is there a need for engine/APU run up (or motoring) ? or just a check BITE is enough?

Feedback appreciated. Thank you.

[spannersatcx]

On an engine the MM states what tests need to be done after changing components. I recently changed and oil pressure switch (CF6-80), only a small item, but as it has seals it reqs a leak check and test to make sure the status msg has cleared and of course indicates.

Off the top of my head one of the things that only needs a bite after replacement is an EEC, no fluids involved so no leak check reqd.

[AeroTech]

Thank you for your post.

I don't have access to maintenance manuals.

Do you need engine run up (like at idle) or just engine motoring to test this oil pressure switch? If aircraft is inside hangar, do you need to tow aircrraft outside to perform this test?

I guess (I might be wrong) other components like N1 or N2 speed sensor don't need leak check since no fluids is involved: do you need engine/APU run up or just engine motoring to perform test or troubleshooting in such components?

When testing or replacing these small components at apron (line maintenance), how often do you need to tow the aircraft to a cleared area to run up the engine if the ramp is conjested, the direction of the wind is not favorable for engine run up...etc.

Feedback appreciated. Thank you.

[spannersatcx]

in this instance it was an idle leak check, I work on the ramp, idle leak checks can be carried out on stand, anything above idle requires a tow to an engine run bay.

None of the hangars I ever worked in allowed engine starts to be carried out inside.

Replacing something like an N1 tacho requires an idle run.

[slapdash8]

any component that requires breaking into a engine fluid system, be it fuel or oil require engine run leak checks. fuel system component changes often require a high power leak check, due to increased fuel flow at higher engine speeds. oil px switches may also need a higher power run, to check for correct indication through the specified range.

in the case of n1 and n2 probes, engine runs are required incase the component is fail on fit, or, to indicate if the probe was infact at fault (as fadec harnesses are often to blame, as i have found out many times)

most airports allow engine runs at grnd idle power on stand for maintenance, leak and function checks etc.