Service difficulty report · Bolt · Dhav DHC8*

Difficulty date
January 14, 2011
Submitted
March 15, 2011
Operation
Air carrier
Make and model
Dhav DHC8*
Engine
Pwa PW120
Propeller
Hamstd 14SF7
Part
Bolt
Part number
MS21250H08056
Condition
Broken
Location
Strut
Part time
44,818 hours
Component
Strut · Dhav · 85320338
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

WHILE INSPECTING FOR POSSIBLE HYD LEAK AT THE RT WING ROOT, MX DISCOVERED THAT 1 OF THE WING BOLTS FOR THE REAR SPAR STEEL SUPPORT STRUTS HAD FAILED. THE BOLT HEAD HAD SEPARATED FROM THE SHANK OF THE BOLT AND WAS DANGLING FROM THE SAFETY WIRE. UPON REMOVAL, IT APPEARS THAT CORROSION MAY HAVE BEEN A FACTOR IN THE FAILURE. THE INCIDENT HAS BEEN REPORTED TO THE MFG AND THE AFFECTED PARTS ARE IN QUARANTINE AWAITING DISPOSITION. THE LOCATION IS AT STA X424.12, Z174.54 ON THE RT SIDE OF THE ACFT AND IS THE FWD OTBD BOLT OF THE REAR SPAR SUPPORT STRUT (HOCKEY STICK). BOLT IS UNDER TENSION. CORROSION EXTENDS UP THE SHAFT OF THE BOLT APPROX 1.5 INCHES FROM POINT OF SEPARATION AT THE HEAD. THERE IS ALSO CORROSION ON THE HEAD OF THE BOLT AT THE RADIUS. CORROSION IS ALSO PRESENT ON THE SHAFT END WHERE IT SEPARATED BUT IT IS NOT KNOWN IF THIS WAS THE CAUSE OR A RESULT OF BEING EXPOSED TO THE ELEMENTS AFTER THE SEPARATION. FINDING(S): THERE WAS NO APPARENT PITTING OR OTHER DAMAGE TO THE STRUT ASSY WHERE THE BOLT PASSES THROUGH. MFG TO COMPLETE FURTHER ANALYSES.