Major or Minor repairs Engines

[Stache]

According to the FAA a Major Repair means the following in accordance with Part 1 definitions.

Major repair means a repair:
(1) That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
(2) That is not done according to accepted practices or cannot be done by elementary operations.

I would like to get as many points of view on what is considered a major repair to an engine. So I would like to refine it to turbine engines. So for example you want to flame spray a turbine blade, of course this takes a process specification or an engineering authority to accomplish, is it major of minor repair.

Take flame spray in general for an accessory case is it a major or minor repair to build up a bearing hole and line bore it? I might mention this is not covered in most/any engine repair manuals I have read.

Looking for help.

Stache

 

[COKA]

Sometimes a certain process or operation may not be used in a specific repair for a specific part, but it may be used on another, similar part in another repair. Also, you have to make sure that you know very well the Standard Practice Manual that goes with that Repair Manual for that particular engine. What you have to look for is the material of the part and where that part goes in the engine. Also, if you have access to different repair manuals and different standard practice manuals, you should compare them. You may be surprised to find your answer in the other manuals.

All that said, a major repair is a repair that will affect / change the operational characteristics of the part that you are repairing. Also, you don't want to change critical dimensions. Another very important point - rotating parts... What may be considered minor on other parts may be very major on a rotating part! Ask yourself the following question every time you are having a doubt: Would I have my wife (husband) and kids (for an aircraft engine) fly in an airplane that has engines with parts that were repaired that way? You will feel the answer.

Coka