SDR EGRA200501

Service difficulty report · Tube · Skrsky S76A

Difficulty date
February 12, 2005
Submitted
August 26, 2005
Operation
Air carrier
Aircraft
N763MH
Make and model
Skrsky S76A
Aircraft serial
760230
Aircraft time
13,873 hours
Engine
Allsn 250C30S
Engine time
14,180 hours, 39,632 cycles
Part
Tube
Part number
23032941
Part serial
NA
Condition
Cracked
Location
Nr 1 Turbine
Component
Turbine · Allsn · 250C30S
Component part number
23035128
Stage of operation
IN
How discovered
V
Nature of condition
K
Precautionary procedure
K

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

What was found

AFTER NORMAL LANDING AND SHUTDOWN AT HOSPITAL A LARGE PUDDLE OF OIL WAS FOUND UNDER THE AIRCRAFT. FURTHER INVESTIGATION SHOWED OIL COVERING NR 1 ENGINE DECK AND OIL QUANTITY WAS DOWN BY THREE QUARTS. OIL TEMP AND PRESS WERE NORMAL AT SHUTDOWN. THE LABYRINTH SEAL SUPPLY TUBE WAS FOUND TO BE CRACKED OFF FROM THE ESHAUST COLLECTOR FLANGE ADAPTER AND MISPLACED ABOUT HALF THE TUBE DIAMETER. THIS RESTRICTED AIR FLOW TO THE LAB SEAL ALLOWED OIL TO FLOW OVER THE LAB SEAL. TURBINE SECTION WAS WITHIN 30 CYCLES OF BEING REMOVED DUE TO TURBINE WHEEL CYCLES. MECHANIC ON DISASSEMBLY REPORTED THAT TUBE MAY HAVE BEEN ORIGINALLY TIGHTENED UNDER A TWISTING LOAD. TURBINE SECTION WAS REPLACED.