After every flight, pilots fill out a form called a gripe sheet, which conveys to the mechanics problems encountered with the aircraft during the flight that need repair or correction.
The mechanics read and correct the problem, and then respond in writing on the lower half of the form what remedial action was taken and the pilot reviews the gripe sheets before the next flight.

Never let it be said that ground crews and engineers lack a sense of humour.
Here are some actual logged maintenance complaints and problems as submitted by Qantas pilots and the solution recorded by maintenance engineers.
By the way, Qantas is the only major airline that has never had an accident.

P = The problem logged by the pilot.

S = The solution and action taken by the engineers.


P: Left inside main tyre almost needs replacement.
S: Almost replaced left inside main tyre.

P: Test flight OK, except auto-land very rough.
S: Auto-land not installed on this aircraft.

P: Something loose in cockpit.
S: Something tightened in cockpit

P: Dead bugs on windshield.
S: Live bugs on back-order.

P: Autopilot in altitude-hold mode produces a 200 feet per minute descent.
S: Cannot reproduce problem on ground.

P: Evidence of leak on right main landing gear.
S: Evidence removed.

P: DME volume unbelievably loud.
S: DME volume set to more believable level.

P: Friction locks cause throttle levers to stick.
S: That's what they're there for.

P: IFF inoperative.
S: IFF always inoperative in OFF mode.

P: Suspected crack in windshield.
S: Suspect you're right.

P: Number 3 engine missing.
S: Engine found on right wing after brief search.

P: Aircraft handles funny.
S: Aircraft warned to straighten up, fly right, and be serious.

P: Radar hums.
S: Reprogrammed radar with lyrics.

P: Mouse in cockpit.
S: Cat installed