Output Number
Approval Date
Published Date Time
Recommendation type
Mode
Date released

The Bureau of Air Safety Investigation recommends that Boeing
Commercial Airplane Group review the effectiveness of Service
Bulletin 737-32A1224.



As a result of investigation into this occurrence, the Bureau
simultaneously issues the following interim recommendations:



IR990019



The Bureau of Air Safety Investigation recommends that Boeing
Commercial Airplane Group alert Boeing 737 operators to this safety
deficiency and implement an appropriate inspection program.



IR990021



The Bureau of Air Safety Investigation recommends that the Federal
Aviation Administration note the above safety deficiency and
interim recommendations and take appropriate action as considered
necessary to ensure the integrity of Boeing 737 main landing gear
actuator beam arm assemblies.







IR990022



The Bureau of Air Safety Investigation recommends that the Civil
Aviation Safety Authority initiate appropriate action to ensure
that Australian operators of Boeing 737 aircraft immediately
inspect all main landing gear actuator beam arm assemblies for
evidence of cracking.



IR990023



The Bureau of Air Safety Investigation recommends that Australian
operators of Boeing 737 note the above safety deficiency and
interim recommendations and take appropriate action as considered
necessary to ensure the integrity of Boeing 737 main landing gear
actuator beam arm assemblies.

Organisation Response
Date Received
Organisation
Boeing Co
Response Text

Recommendation IR990020 states that Boeing should review the
effectiveness of Service Bulletin 737-32A1224. Prior to the
original release of the bulletin in 1989, operators were reporting
medium - to - heavy corrosion of the beam arms (in addition to
several reports of fractures). Following the second post - bulletin
fracture report (dated 6 October 98 in the table above), we
conducted a survey of operators and asked for an assessment of the
condition of beam arms in service. In general, most operators who
responded (representing just over 1300 airplanes) reported very
little (if any) corrosion. The basic response is that, although the
bulletin appears to have been effective in reducing the reported
corrosion, it has not eliminated the potential for corrosion which
leads to the possibility of cracking of the beam arm lugs.
Therefore, we are undertaking the actions as noted in the response
to recommendation IR990019 above.