The Australian Transport Safety Bureau recommends that the
Federal Aviation Administration (Piston Engine Certification
Directorate) review the practice during assembly of applying
anti-galling compounds to the backs of connecting rod bearing
inserts with respect to its affect on the safety margin for engine
operation of the bearing insert retention forces achieved.
The Office of Accident Investigation is in receipt of your recommendations regarding "PA-31-350 Engine Failure."
Your recommendations have been forwarded to the appropriate office for response, which is normally 90 days. Your recommendations have been identified as 02.141 and 02.142 and inquiries should reference these numbers.
You will be kept informed as to the progress and final resolution of your submission. If you have any questions or need additional information regarding these safety recommendations, please notify [Name Supplied], AAI-210, at [Telephone Number Supplied].
I refer to two safety recommendations that the ATSB issued to the FAA in December 2001 that arose from the ATSB's investigation into the Whyalla Airlines PA3l-350 accident that occurred on 31 May 2000.
In your letter of 5 August 2002, you advised that an FAA Safety Recommendations Review Board had classified responses to recommendations 02.141 and 02.142 as "Closed -Acceptable Action". The memorandum attached to your letter outlined the action that the Aircraft Certification Service, Engine and Propeller Directorate intended to take concerning the recommendations. As it is now over 12 months since receiving your correspondence, I wanted to check with you regarding the progress the FAA has made in examining those issues.
Further, our investigation into the engine malfunctions in the accident aircraft, as well as engines that had malfunctioned in other aircraft, revealed clear evidence of corrosion damage to the aluminium alloy layer in the bearings where the alloy was exposed at the bearing insert ends. The ATSB's report on the accident stated that the formation of lead oxy bromides instead of lead bromide would affect the quantity of free bromine remaining after the scavenge process. Excess bromine can find its way into the lubricating oil and form hydrobromic acid. The ATSB would also be interested in any observations or data the FAA might have gained regarding excess bromine from the evaluation of piston engine performance characteristics it was conducting.
Subsequent to the ATSB response of 9 October 2003, the ATSB has released a research report into aircraft reciprocating-engine failures, B2007/0191 . The ATSB now closes this recommendation.
