Has there ever been an accident investigation in which FDR data from a prior, seemingly uneventful flight was useful, for example by showing that a problem had begun to develop prior to the accident but had not been noticed?
I did a quick search online, it confirms previous flight recordings have been used and a link with the accident evidenced. Investigation agencies obviously try to make the most of the material they can get, I don't know how often looking at previous recordings brings additional elements.
Two random examples:
An aircraft accident in Russia, in 2013, investigated by Russian IAC, and
the Germanwings accident in 2015, investigated by French BEA.
VQ-BBN in 2013, approach at Kazan International Airport (UWKD), Russia
Boeing 737-53A operated by Tatarstan Airlines. ASN:
The need for a go-around was caused by the position of the aircraft relative to the runway, which was the result of "a map shift" effect (Map shift, an error in the determination of the aircraft position by onboard systems) by about 4 km, the crew's inability in the circumstances to integrated piloting and maintenance of navigation with the required accuracy, and the lack of active assistance of the air traffic control service under the long-term monitoring of significant deviations from the approach procedure.
The recordings of older flights were used to show the repeated map shift and the offset trajectory of the aircraft at multiple times for the the same approach. The report includes plotting of related approach ground tracks.
From the investigation report of the Interstate Aviation Committee (IAC):
The analysis of previous PIC flights FDR record (Section 1.18.8) revealed that ...
- during the previous approaches there were instances when IRS current position errors reached significant values that could be compared with the error remarked in the accident flight. The start of the base turn during all approaches was matched the approach pattern with an acceptable accuracy.
- in all cases when there was significant deviation of the actual flight path from that calculated by the IRS, the crew deactivated L-NAV mode well in advance and entered the base turn point with HDG SEL mode engaged.
- during all approaches the crew engaged the VOR/LOC in due time, which ensured the aircraft intercepted the localizer in automatic mode.
IAC concluded the problem with the map was not new, there was no maintenance initiated.
D-AIPX in 2015, Pilot suicide while overflying French Alps
Airbus A320-211 operated by Germanwings (ASN)
From the investigation report:
All of the data from the previous flight, from Düsseldorf to Barcelona, was recorded on the FDR. The recordings from the CVR included the last 50 minutes of this flight.
The BEA noted what can be interpreted as a attempt to crash the plane in the previous flight. This happened, like for the actual accident, while the captain had left the cockpit.
The autopilot altitude was set briefly, at multiple times, to 100 ft. The BEA also tried to exploit the QAR (the non-protected data recorder used by the maintenance team), but it was too damaged for retrieving data.