CASA acknowledges the intention of the safety recommendation and
advises that the Authority has taken significant steps to address
this issue with the Federal Aviation Administration in relation to
the, certification of the Piper aircraft and engine.
In discussions with the Federal Aviation Administration (FAA) New
York Aircraft Certification Office and the FAA Atlanta Aircraft
Certification Office, CASA advised that one of the primary issues
identified in the Whyalla accident was aggressive fuel
CASA advised the New York and Atlanta FAA Offices of the
discrepancies identified between the Engine Operating Manual
approved by the New York Office and the Aircraft Flight Manual
approved by the Atlanta Office.
Following these discussions, the Atlanta Office has responded with
advice that the FAA is of the opinion that fuel mixture leaning
procedures were not a contributing factor in the events of May
This response is not consistent with the findings of the ATSB in
regards to the resulting combustion chamber deposits, preignition
CASA's actions in regards to this recommendation are ongoing, and
discussions are being held with the engine manufacturer. CASA
undertakes to advise the ATSB of the outcomes of these discussions
as they progress.
In relation to the maintenance procedures for all high-powered
piston engines fitted to Australian registered aircraft, CASA
advises that action in relation to this matter is ongoing.
CASA intends to review current maintenance procedures applied to
all high-powered piston engines fitted to Australian Registered
aircraft to ensure compliance with manufacturer's published
procedures, and in the opinion of the Authority, this action will
provide timely notice of engine distress resulting from combustion
In relation to the operating procedures for all high-powered piston
engines fitted to Australian Registered aircraft, CASA advises that
the Authority has notified all operators of Textron Lycoming and
Teledyne Continental Motors piston engines aircraft of reports of
crankshaft bearing failures.
To minimise the risk of combustion chamber deposits resulting in
abnormal loading of the bearings, CASA has recommended the
operators adopt conservative fuel mixture leaning procedures.
A copy of this letter is provided for the information of the
The following is a copy of the letter
To all operators of Textron Lycomiag and Teledyne Continental
Motors piston engines with a take off power rating greater than 250
And aircraft maintenance organisations
Subject: Lycoming and TCM Crankshaft Bearing and Connecting Rod
Since August 2001, CASA has received 9 major defect reports
relating to crankshaft and connecting rod bearing failures. Six of
the failures occurred in Lycoming engines and three in TCM engines.
All of the failures have occurred at a low bearing time in service.
All but one of the reports involved large, high horsepower engines.
A preliminary examination of a number of the failed bearings
indicates evidence of delamination of the bearing shell layers.
That examination result is consistent with undocumented reports of
warranty claims against engines exhibiting bearing material in the
oil filters of low time in service engines.
Textron Lycoming, Teledyne Continental Motors, Superior Air Parts
and the FAA have been advised. of the bearing defects being
reported in Australia CASA is conducting on-goingdiscussions with
Lycoming, TCM and Superior Air Parts on the reported failures.
'However, CASA, has been advised; crankshaft bearings can also be
supplied by non original equipment manufacturers each with a unique
prefix to the original part number. Air Support and Engine
Components Incorporated are two such suppliers. An Air Support
supplied bearing will have the prefix "AS", eg; AS 13884-M03
Textron Lycoming has advised; bearing delamination detects should
not present a safety of flight concern if the engine oil pressure
filter and oil pressure screen are inspected for metal
contamination at each oil and filter change. Cutting open the
filter and examining the filter element as detailed in Lycoming
Service Bulletin Number 480D will provide ample opportunity to
detect an impending bearing failure. The FAA supports the Lyconung
Aggressive fuel mixture leaning may be relevant to the reported
bearing defects.' The Australian Transport Safety Bureau, in
investigating the dual engine failures associated with the fatal
Whyalla Airlines Piper PA31-350 accident, noted a relationship
between bearing failures and aggressive fuel leaning procedures.
The ATSB lists engine operating practices as a contributing factor
in that accident. A copy of the ATSB report can be found on the
internet at www.atsb.gov.au. The CASA Flight Safety Australia
Jan/Feb 2001 "Lean and Mean" article advising of the real costs of
aggressive fuel mixture leaning also provides useful information on
Until a full understanding of the causes of the crankshaft bearing
failures is obtained, CASA recommends all Lycoming and TCM piston
engine powered aircraft operators and applicable maintenance
organisations carry out the following precautionary
1. Fuel mixture leaning procedures detailed in the aircraft
manufacturer's flight manual or pilot operating handbook may be
different to the procedures recommended by the engine manufacturer.
The engine manufacturer may recommend the use of richer fuel
mixtures than those approved by the aircraft manufacturer. To limit
crankshaft bearing exposure to abnormal combustion loads occurring
during aggressive leaning procedures, observe the fuel mixture
leaning procedure limits detailed in the engine manufacturer's
2. At each engine oil change and filter change, if applicable to
the engine model, inspect the oil pressure screen, oil suction
screen and cut open the oil filter and inspect the filter element
for evidence of metal contamination, Lycoming SB 480D and TCM SB
M87-12 Rev.l refer; and
3. Carry out an engine oil change and, if applicable, an oil filter
change, at intervals as published by the engine manufacturer,
Lycoming SB 480D and TCM SB M87-12 Rev. l refer; and
4. At each engine oil change, drain the oil whilst the engine is
still hot and strain the oil through a fine mesh screen filter. If
a bearing defect is present, hot oil will flush out bearing
Defects found in carrying out the above recommendation should be
reported to CASA on the Major Defect Form available from the CASA
website, www.casa.gov.au. CASA is continuing to seek an
understanding on the primary cause of the bearing defects, in
submitting such defect reports, please include all available
information on the supplier and part number of the bearings