Service difficulty report · Turbine · Lear 55LEAR

Difficulty date
July 25, 2011
Submitted
January 23, 2013
Operation
Air carrier
Make and model
Lear 55LEAR
Aircraft time
8,511 hours
Engine
Garrtt TFE7313A
Part
Turbine
Condition
Failed
Location
Engine
Part time
8,484 hours
Stage of operation
TX
How discovered
O
Nature of condition
O
Precautionary procedure
E

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

What was found

(CAN) AFTER ENGINE START THE PILOTS HEARD A STRANGE SOUND FROM THE NR 2 ENGINE AND IMMEDIATELY SHUTDOWN. MX CONTACTED MFG WHO INSTRUCTED THE PILOTS TO RUN THE ENGINE AND PERFORM A SERIES OF CHECKS. DURING THE RUN THE ACFT TEMPERATURE STARTED TO CLIMB TOWARDS RED LINE AND SO THE ENGINE WAS IMMEDIATELY SHUTDOWN. THE ENGINE WAS REMOVED AND SENT TO MFG. TEAR-DOWN REPORT IS AS FOLLOWS: WE HAVE REMOVED THE LPT MODULE AND FOUND 1ST LPT BLADES WITH MISSING SHROUD TIPS. IT IS ALSO EVIDENT THAT THE LPT STUB SHAFT HAS CONTACTED THE INSIDE OF THE HP SHAFT AS WELL. THE HP SHAFT SNAPPED AS WE WERE REMOVING THE HPT DISC. TYPICALLY, THE 1ST LPT SHROUDS FAILED WHICH SHOOK THROUGH THE LPT MODULE SEVERELY OUT OF BALANCE WHICH ALLOWED THE LPT MODULE TO "WHIP" AND THE LPT STUB SHAFT THEN CONTACTS THE HP SHAFT CAUSING IT TO RUB AND EVENTUALLY FAIL.