Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-09-16
March 3, 2009
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) reminds owners
and operators of the Cessna twin engine aircraft listed below of the
importance of carefully inspecting the main landing gear (MLG) torque
tubes per the applicable structural inspection document (SID) and
making sure the landing gear are properly rigged.
At this time, the airworthiness concern is not an unsafe condition that
would warrant airworthiness directive (AD) action under Title 14 of the
Code of Federal Aviation Regulations (14 CFR) part 39.
Background
Recently the FAA learned of an incident involving a Cessna 401
airplane. The Cessna’s right MLG collapsed on rollout following an
otherwise uneventful flight. Although it was unrelated to the gear
collapse, subsequent investigation revealed a fatigue crack in the MLG
torque tube. Such fatigue cracks could cause failure of the torque tube
and result in failure of the gear to retract.
The gear collapse was thought to be caused by a mis-rigged downlock
switch. Proper landing gear rigging is critical for safe operation of
the landing gear.
The August 2006 issue of AC43-16A has some very good pictures of a
cracked 5045010-19 torque tube removed from a Cessna 414 with the
following caption “The L/H main gear bell crank assembly (P/N
5045010-19) cracked and failed when the gear was selected to ‘up’.”
There are many other service difficulty reports (SDRs) that show when a
torque tube fails, the main gear does not retract fully and the pilot
sees a discrepancy in the gear warning light system.
Recommendations
We recommend that owners and operators of the aircraft listed in the Introduction section ensure:
their maintenance personnel
review pages 9-10 of the August 2006 issue of AC43-16A
(http://www.faa.gov/aircraft/safety/alerts/aviation_maintenance/media/2006/2006_08_Alert.p
df);
the pilots give feedback to
the maintenance facility when a gear retraction anomaly occurs (when
one main gear does not retract it is possible to see a discrepancy in
the gear warning light system or a noticeable drop in climb or cruise
speeds);
their torque tubes are cleaned and carefully inspected per the applicable Supplemental Inspection Document (SID); and
their maintenance personnel properly rig the main landing gear per the applicable maintenance manual.