While in cruise flight, the crew of the SA 227 aircraft noticed
the left engine oil pressure fluctuating. A visual inspection of
the engine in-flight revealed nothing unusual. A short time later,
the left engine oil warning light illuminated and, in accordance
with company standard operating procedures, a precautionary engine
shut down was carried out. The crew then diverted the aircraft to
the nearest available airport and conducted a single engine
approach and landing. A post flight inspection of the aircraft
revealed no measurable oil remaining in the left engine.
An inspection of the aircraft, immediately following landing,
found that the engine oil had leaked from a loose right-angle oil
line fitting that was situated on the left engine's Beta Manifold.
A subsequent maintenance investigation by the operator discovered
that the fitting had become loose after it had been forcibly
contacted by the left starter generator's "micarta" electrical
connector block. That contact had occurred following the rotation
of the generator on its mounts due to a loose attaching clamp and
several missing locating pins.
An inspection of the generator's attaching "v-band" clamp
revealed evidence of deterioration of the thread and nut that
tightened the clamp. Three of the four locating pins that
positioned the generator on the mount were also noted to have been
missing, with the remaining pin partially depressed into the
surface of the mount. The generator had been removed, and
re-installed, during contractor maintenance approximately two weeks
prior to the incident.
The starter generator and mounts were replaced with serviceable
items and the engine was ground run with no problems noted. The
aircraft was returned to service.
Following the incident the contract maintenance personnel were
briefed on the occurrence and the ramifications of incorrect
component installation.