the seals of aircraft i maintain are contnuously leaking wat cd be cause?

Question

at first the seal of starter was found leaking when we rectified that in the next flight we saw that the seal of propeller was leaking. after replacing the seal three times we found leak in FCU.when we replaced that seal,seal of freon compressor drive coupling started leaking.in the last flight we replaced that seal and now we again detected a leaking starter seal. can anyone help me. the type of aircraft is super king air B-200.

Answer 1

Typically leaking seals are caused by a few problems.
If the seal is sealing a shaft from a case, drive, crankcase, the seal could be riding on a part of the shaft that has been worn down by older seals. If this is the case you need to move the seal inboard or outboard on the shaft so that it rides in a non-worn down spot.
In addition, the shaft could have bad bearings, allowing excessive lateral movement against the seal. Its hard for a seal to work when it is constantly fitting a shaft that moves around in ways in which it ways never designed to.
Also, the seal could be made of a material that gets deteriorated by the type of fluid it is sealing. In this case the seal will in short time fail. Check the seal and see if signs of deterioration are occurring.
Inspect the seals and see if any signs of wear are present. Then go from there.

Answer 2

Is this a cargo plane? It is possible that the seals may have been exposed to a corrosive gas. Fumes from the fuel may do it if it's running cheap fuel. Could also be that the aircraft sat for a long time and the seals dried out. Definitely sounds like SOMETHING caused this problem. Do you think it may have been caused by an exposure to extreme altitudes or shock from a change in altitude that was too fast causing the metals to shrink and expand too quickly, tearing the seals? Not much more to think of. I think the latter may be the most likely as it just doesn't seem possible that all of these seals could get exposed to harmful fumes as they are somewhat protected in the lines. Best of luck.