What are the rules governing when a commercial airliner must be flight-tested before carrying passengers, following a repair?
It is obvious that many minor repairs and maintenance work are performed all the time without flight tests, i.e. the first flight after the repair is a scheduled commercial flight. And presumably, if an airplane sustains major structural damage that must be repaired (e.g. from a hard landing, bird strike, jetway collision, etc.) a flight test is required. Where is the dividing line? Is there any law controlling this in the US, or is it up to the individual airlines?
I was taking a connecting flight somewhere where there was trouble securing the door closed. Besides the maintenance people who went to the flight line to repair the door, an FAA inspector accompanied them.
It’s defined in various FAA-driven regulations the details of which are way beyond me as a pilot.
But I do know that formal airliner test flights are not commonplace. They are required after major overhauls on the jet, which happen every few years. I do NOT think they’re required after an engine change.
There are very few if any repairs which actually require an inspection by FAA personnel. FAA does have inspectors, but mostly they wander around and watch whatever work happens to be being done that day. Doesn’t matter if it’s changing a tire, refilling hydraulic fluid, or changing an engine; The FAA’s interest amounts to: Did you have current manuals available and refer to them? Did you do the work per the manual? Did you fill out the paperwork correctly?
Many FAA maintenance inspectors are not themselves qualified maintenance workers. They just know the rules & monitor compliance with them.
There are some events which require extensive inspections, such as hard landings, flap overspeeds, etc. They may take many man-hours to accomplish. But a test flight is generally not part of the return to service process.
That’s the best I can do from experience without digging into the regs.
FYI, a lot of airline regulation is done via documents called “approved specifications”, wherein an airline writes up their proposed procedures and the Feds bless them. Once blessed these have the force of law for that carrier. But they are NOT available online since they are more or less private agreements between the FAA and that carrier. Generally the carriers of any given tier of the industry all share a common baseline set of specs which formalize the common industry practice. But there is always a bit of *a la carte *difference between any two carriers’ specs.
I worked on the military version of a commercial aircraft - the DC-9 and business jet - the Sabreliner. If I remember correctly, the only normal FCF (Functional Flight Test) requirement was if both engines were changed at the same time.
Also coming out of a major depot inspection where the aircraft was really torn down and reassembled.
Of course these could have been more of military requirements than FAA; however, we did follow FAA requirements pretty closely.
Educated guess follows: I would think the FAA / CASA / CAA rule would boil down to “A test flight is required when the manufacturer says it is.” The manufacturer then produces maintenance manuals containing the requirements for maintenance and any post maintenance checks. The manuals are approved by the FAA as part of the aircraft certification process. This way the detailed requirements are only written in one place but the FAA still has oversight.
My guess would also be that damage repair is negotiated with the manufacturer at the time as any damage will be unique and not easily able to be defined by all encompassing rules.
I know that our aircraft are not test flown after engine changes. They are not required to be test flown after scheduled heavy maintenance (“C” check) but we do it anyway. And it’s not really a test flight, just a functionality check.
When the Lockheed P-80 was first adopted by the USAF, the engines had to be replaced/rebuilt after 10 hours. Hey, it was the first operational jet, okay? Chuck Yeager was then assigned as a Maintenance Check pilot at Wright Pat. It didn’t take long for him to acquire more hours in jets than any other pilot on the base. That’s how he got into Flight Test sort of through the side door.
No it wasn’t. There were several European jets produced in the late 30s/early 40s and the British Gloucester Meteor first flew on 5 March 1943, and the German Me 262 was a few months later. The P-80 did not go into service until 1945.
I can tell you that we had to flight test our Hawker 800 after removing and reinstalling the wing leading edges. The precise alignment of the leading edges is critical to flying characteristics, and the manufacturer determined that it needed to be verified via the performance of an aerodynamic stall series with a factory test pilot. Had they been misaligned, one wing would have stalled before the other, leading to… undesirable behavior.
