I feel like an idiot now… I can’t believe I filled up my own compass without a volume of paperwork 
. Clearly my airplane can’t fly now without some signatures!
Just joking, I don’t own that airplane anymore. However, in Canada, I have always found the mechanic I worked with (who was freelance) to have a safety conscious, rule conscious, and PRAGMATIC approach to dealing with airplanes made in 1946…
Would you write out your own MOT certificate?
I don’t have MOT certificates or similar for any car or motorcycle I own… because they aren’t required… shock, horror.
In Canada I don’t have an MOT. I am responsible for the safety of my vehicle. Double shock and horror!!
Silvaire wrote:
don’t have MOT certificates or similar for any car or motorcycle I own… because they aren’t required… shock, horror.
Are’nt you residing California ?
If so, then you have the bi-annual “Smog check”, albeit, there are many exemptions.
But more to the point: would you willingly break the law and ignore it if there was one ?
That said, I would agree that not allowing A&Ps to service a wet compass or perform a compass swing makes little to no sense whatsoever.
So, back to the topic – could an A&P overhaul the landing gear pump, if say there was a diagram available showing the exploded view and the various part numbers?
An overhaul manual will generally contain fits and clearances which won’t be shown on a general assembly drawing. In addition, there will be a return-to-service test procedure – flow rates, pressure limits etc, so without this data, how can the unit be declared serviceable on completion?
As a EASA/FAA repair station, we have to hold (and as stated before, confirm via auditable subscription) continued access to current maintenance data. Where OEM data isn’t available (perhaps it never existed or the OEM is no longer trading), there are procedures available to allow the maintenance company to generate suitable data themselves, but these are still subject to oversight/approval as part of the C rating process.
OK, let me move the goalposts a little.
Let’s assume this gear pump is fine but the motor is faulty (the usual case with aircraft gear pumps). Motor faults are commonly
We don’t have an answer above for the A&P overhaul scenario, but would it in any case be legit for the engineer or the repair station to send the motor off to a normal motor repair company and get it repaired and then inspect it and re-assemble the pump? There are going be very very few motor repair companies with FAA or EASA 145 approval.
In addition, there will be a return-to-service test procedure – flow rates, pressure limits etc, so without this data, how can the unit be declared serviceable on completion?
Speaking in purely engineering terms, the pump can hardly not be delivering the flow rate and the pressure IF the motor is working and the pump mechanism isn’t totally buggered. A functioning motor, drawing the right current at the right voltage, will be outputting the right power.
It’s exactly the same with aircraft engines. They make pretty well the same HP unless totally shagged – because the HP is determined by the geometry (piston sizes, the crankshaft stroke, valve lift and timing etc), the fuel flow (an overhauled fuel servo will have been checked for the fuel flow / airflow curve) and the airflow (assured by air duct geometry and lack of dead birds, etc).
This is true for most simple mechanical things. Correct working is easily verifiable, and in this case you can see soon enough when you install it and work the gear.
Now, on the topic of brushes… what privileges are needed to change motor brushes, where there is no repair or overhaul data available?
Peter, I believe an FAA A&P mechanic electric motor overhaul using commercial subcontractors is legal if the A&P has approved data for the materials and process used in the overhaul and is available in person to supervise the work. In those requirements it is no different than supervising me (an uncertificated ‘mechanic’) and signing off my work on the plane itself. In the case of the electric motor, I think it would be difficult to get the approved data… if (for example) you wanted to rewind/reinsulate the windings.
For engines, the overhaul data is more widely available and it is similarly legal for an A&P mechanic to supervise a commercial (e.g. airboat engine) machine shop in reworking engine parts, then sign off the engine overhaul himself. I know an A&P who overhauled the AEIO-540 on his certified N-registered Extra that way, quite a large engine, and a very nice job it was too.
I think if you dig deeply enough into any example of FAA regulations in aircraft maintenance, there are grey areas. FAA quite sensibly does not attempt to create a ‘perfect’ system and then force people to operate to the letter of that ‘perfect’ system. Instead they laid out a simple framework, let individuals and businesses figure out how they can best operate within the imperfect but clearly documented framework (in their own way) and then fix specific regulatory problems that through experience are shown (by evidence) to have led people into doing something that caused an accident. Hence FAA = Fix After Accident. It works well and efficiently in the real world even if it seems to make the rather less experienced EASA ‘geniuses’ nervous. 
In practise I’ve never had an issue with repairs on the FAA system. For example, once the generator (originally an old tractor part – the ancient International Harvester tractor we use at the glider club I’m sure has the same dynamo) packed up on my old Cessna 140 the best part of 1000 miles from home. I found an old airport geezer and son A&P/IA outfit, and they overhauled my generator on the spot (including taking the armature to a commercial electrical machines repair shop) and made the appropriate logbook entries, and I was on my way. There was no handwringing over approved data. A generator (like a motor) is a pretty simple device. This is how it works in practise.
