SDR 2007FA0001111

Service difficulty report · Thru Bolt

Difficulty date: December 17, 2007
Submitted: December 28, 2007
Operation: General aviation
Engine: Cont IO520C
System (JASC): 8520 · Reciprocating Engine Power Section
Part: Thru Bolt
Part number: SA6419311075
Condition: Broken
Location: Crankcase
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

INSTALLING ALL NEW SA641931-10.75 LOT NR K070059179, REV E THRU BOLTS IN ENGINE. AFTER TORQUE, WITHIN A FEW HOURS THE THRU BOLT SNAPPED, AT THE OIL RING GROOVE. THIS IS THE THIRD THRU BOLT THAT HAS SNAPPED AFTER TORQUE, AND SETTING. PROBABLE CAUSE, IS IMPROPER HEAT TREATING DURING OR AFTER PLATING. (K)