Service difficulty report · Nut · Hughes 369FF

Difficulty date
October 27, 2008
Submitted
January 20, 2009
Operation
General aviation
Aircraft
N5185G
Make and model
Hughes 369FF
Aircraft serial
0009F
Engine
Allsn 250C30
Part
Nut
Part number
MS210435
Condition
Backed Out
Location
Cooler Blower
Component
Blower
Component part number
359025630101
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

OIL COOLER BLOWER DRIVEN PULLEY RETAINING NUT IS BACKING OFF OF SHAFT DURING NORMAL USE. NUT IS A STAINLESS STEEL, SILVER PLATED, ALL METAL SELF LOCKING TYPE NUT. THIS WAS THE 3RD OCCURRENCE OF THIS TYPE FOR OUR UNIT AND WE ARE ALSO AWARE OF ONE OTHER INCIDENT TO ANOTHER COMPANY. WHEN THE NUT BACKS OFF IT CAUSES THE SHAFT BEARING TO GO BAD WHICH DESTROYS THE OIL COOLER BELT. THIS LEADS TO EXTREME ENGINE OIL AND MAIN TRANSMISSION OIL TEMPERATURES. AFTER INVESTIGATING PN, WE FOUND THAT MFG HAS BEEN USING THIS TYPE NUT FOR A LONG TIMEAND WERE UNSURE IF THE NUT CURRENTLY BEING PRODUCED ARE SUBSTANDARD. UNIT WAS O/H. THE O/H FACILITY HAS BEEN INFORMED OF THESE INCIDENTS AND THEY ARE CURRENTLY INVESTIGATING THE MATTER. (K)

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