CC130617 Hercules-J - Epilogue

Report / July 1, 2012 / Project number: CC130617-C-Cat

Location: 8 Wing Trenton, ON
Status: Investigation Complete
Date: 01 July 2012

Early in the morning of 1 Jul 12 (0212Z), contracted personnel working on a CC150 Airbus in 10 Hangar heard a loud noise and noticed that the Hercules in the adjacent Bay 5 was rocking from side to side.  Upon closer inspection, they noted that the left main wing jack had collapsed and damaged the left main landing gear door.  The right main wing jack had come off its jacking pad and penetrated approximately 17 to 20 inches into the wing.  No fuel cells were ruptured.  The right nose jack also came off its jacking fitting and torsional deformation of the airframe was noted on the aircraft fuselage skin near the left nose jacking position.

The aircraft had been on jacks for four days prior to the occurrence.  There were no injuries as no one was working on the aircraft at the time.

The investigation determined that the dimensions of key jack components (tension post and bolts) did not meet engineering design requirements.  This resulted in three bolts attaching the tension post to the lift unit having only three threads engaged vice the six to seven threads engaged on a jack that is built to specifications.  Furthermore, an incorrect jack levelling procedure exacerbated the weakened bolt thread engagement that then allowed the lift unit casting threads to strip under overload, triggering the collapse.

The safety recommendations focus on ensuring parts used are in accordance with design specifications and on developing a correct jack leveling procedure.

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