Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
NM-07-27
April 17, 2007
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) advises you,
owners and operators, of Boeing Company Model 747-400F Series, Line
1361 – 1366 airplanes of a decision made by the FAA which relates to
the number nine main deck side cargo door latch back-up fitting and
Boeing Commercial Airplane Group’s Alert Service Bulletin 747-53A2659.
Background
Boeing records indicate the number nine main deck side cargo door
(MDSCD) latch back-up fitting at Station 1897 was not correctly heat
treated to engineering requirements. Heat treatment at the incorrect
pressures, temperatures, and time may result in hydrogen embrittlement,
thus ultimately could result in the failure of that part.
The FAA has concluded that this is not a unsafe condition because this
manufacturing defect only relates to one of ten MDSCD latch back-up
fittings. By design, the door latching system is safe with the failure
of one of the ten latch fittings. Therefore, we have decided not to
issue an AD at this time.
Recommendations
It is FAA’s recommendation that owners and operators of the
affected airplanes be aware of this decision and refer to Boeing
Commercial Airplane Group’s Alert Service Bulletin 747-53A2659 for
guidance on inspection and replacement of the number nine MDSCD latch
back-up fitting.