A U.K. Air Accidents Investigation Branch (AAIB) probe into a shock absorber bolt that broke due to fatigue shed light on a bigger issue: detecting when flight data monitoring equipment is not functioning.
In the August 2015 incident, a BAe 146-200 operated by German charter carrier WDL Aviation that was parked at London City Airport after a flight from Frankfurt was found to have dripped oil around the right main gear. The culprit was a leak created by a broken shock absorber bolt head. Investigators determined the bolt had been in place for about 21,000 landings, well past its 18,100-landing fatigue-life limit. WDL acknowledged it “was unaware of the need to keep a record of the number of landing cycles that the bolts had experienced.” The carrier has added this to its maintenance program.
In addition to the flight data and cockpit voice recorders, the BAe 146-200 was equipped with a quick-access recorder (QAR) that captured data on a flash card. Investigators pulled the QAR, installed to support the operator’s flight data monitoring program, but found no data on the card. Inspection of the recorder found damage to pins that are part of the data interface between the recorder and the card—likely damaged due to improper card installation.
A check of other WDL Aviation QARs found two more with similar damage. The operator published an internal bulletin on correct card installation, similar to one put out by the unnamed QAR maker in 2005.
More troubling was the discovery that the unit’s 28-day download cycle had not yielded any data in two successive downloads.
“Detection of this anomaly would have allowed the faulty QAR unit to be repaired or replaced at an earlier date,” AAIB stated.
AAIB noted that the unit’s fault light did not illuminate while the card was inserted, despite the bent pins. Removing the card triggered the fault light—a sequence that led AAIB to query the QAR manufacturer to ensure it is correct. The report does not detail the manufacturer’s response.