ACFT EQUIP PROB.

Narrative

UPON TAXI OUT LOST OIL PRESSURE. SHUT DOWN ENG. TAXIED BACK TO GATE. FOUND OIL CAP OFF. CAP HAD BEEN CHKED PRIOR TO TAXI. MECH THINKS .041 SAFETY WIRE ACTED AS SPRING TO LIFT OIL CAP 'EAR' AND REMOVE CAP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE CAP HAD BEEN REMOVED ON THE #1 ENG FOR A VISUAL OIL LEVEL CHK IN COMPANY OF THE MECH BECAUSE THE SIGHT GAUGE WAS TOO DIRTY TO ACCURATELY DETERMINE THE OIL LEVEL DURING THE PREFLT. THE ENG IS MADE BY A WELL KNOWN JET ENG MANUFACTURER. THEY HAD INSTALLED BAFFLES ON ALL THEIR ENGS AS A RETROFIT SO AS TO PREVENT OIL LOSS IN CASES OF THE OIL CAP COMING OFF. POST FLT INSPECTION REVEALED THAT THIS ENG DID NOT HAVE THE BAFFLES INSTALLED. MURPHY'S LAW IN ACTION? THE WIRE THAT HE REFERRED TO AS 'LIFTING THE EAR OF THE CAP' WAS A WIRE DESIGNED TO BE A 'TETHER;' TO KEEP FROM LOSING THE CAP IF IT WAS DROPPED OR DID COME OFF. THE WIRE WAS NOT THE PLIABLE; LIGHT TYPE BUT A HVY GAUGED ONE; ABOUT THE WT OF A COAT HANGER. THE MECH THINKS THAT THIS LOOPED UP AND THEREBY LIFTED THE CAP OFF IT'S CROWN. RPTR HAD HEARD OF THIS HAPPENING A LONG TIME AGO BUT NOT SPECIFICALLY ONT THE EMB-120 TYPE ACFT. RPTR HAS CHKED HIS OTHER ACFT VERY CAREFULLY ON PREFLT TO MAKE CERTAIN THE WIRE IS THE LIGHTER GAUGE WIRE.