Plane & Pilot
Tuesday, May 6, 2014

More Alerts For GA Pilots

No matter how extensively you test on the ground, the proof comes in the air

The hydraulic power pack was replaced with a used unit. Both a normal landing gear swing and an emergency gear extension check were conducted. During the testing, leaks were found at the hydraulic pack fittings. They were fixed by installing new seals in the fittings.

After the airplane was removed from the jacks, an engine ground run was performed in order to test the engine-driven hydraulic pump and operation of the flaps when powered by engine-driven pump hydraulic pressure. Then, the airplane sat for a couple of days to confirm that there were no hydraulic leaks.

The airplane was then taken up for a test flight. The landing gear retracted and the flaps operated normally, but the gear didn't fully extend. The pilot extended the gear using the emergency extension hand pump and landed uneventfully.

Then, the hydraulic pump was replaced with an overhauled unit. The gear and flap systems tested satisfactorily on the ground. After that, the airplane went on the accident flight.

The hydraulic pump from the accident airplane tested satisfactorily. Although the hydraulic pack functioned properly in bench testing, there were discrepancies including valve leakage and wear, deformed O-rings and a fine black residue on some components.

The NTSB determined that the probable cause of this accident was an undetermined failure of the hydraulic power pack to fully extend the main landing gear through both the normal and emergency systems.

Convair CV-580
A Convair CV-580 crashed while attempting to return to the Rickenbacker Inter­national Airport (LCK), Columbus, Ohio. The flight had just departed from runway 5L at LCK. The captain, first officer and an observer received fatal injuries. The Part 91 post-maintenance check flight was to end at Mansfield Lahm Regional Airport (MFD), Mansfield, Ohio. The airplane was on an IFR flight plan in visual conditions.

The airplane had been in for maintenance checks, which included flight control cable rigging. At noon local time, the flight received its takeoff clearance, and the takeoff roll began at about 12:03 p.m.


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