Service difficulty report · Bracket · Bell 407

Difficulty date
March 29, 2018
Submitted
October 23, 2018
Operation
General aviation
Aircraft
N766MT
Make and model
Bell 407
Aircraft serial
54540
Part
Bracket
Part number
D02962
Condition
Broken
Location
Zone 200
Part time
795 hours
Component
Rotor Brake · Bell
Component part number
427340352113
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

AFTER PERFORMING A 3600 HOUR ROTOR BRAKE CALIPER OVERHAUL ON CALIPER P/N:427-340-352-113, S/N: 644 THE CALIPER WAS SENT BACK TO THE CUSTOMER AND AFTER SOME TIME WE WERE NOTIFIED, AT A TSO OF 106.5 HOURS, THAT THE SUPPORT BRACKET P/N:D0296-2 HAD BROKEN IN TO TWO PIECES AT A POINT WHERE THE TWO BOLT HOLE TABS COME TOGETHER IN THE CENTER OF THE BRACKET AND THEY WERE RETURNED TO US FOR REPLACEMENT. THIS WAS THE FIRST TIME THIS HAD BEEN NOTICED OR HAPPENED DURING OUR OVERHAULS OF THIS PART NUMBER OF CALIPERS. WE HAVE SINCE BEGUN A MORE THOROUGH INSPECTION OF THE SUPPORT BRACKETS IN QUESTION BY REMOVING ALL OF THE PAINT, TO ALLOW FOR A BETTER VISUAL INSPECTION OF THE BRACKETS TO IDENTIFY ANY CRACKING TAKING PLACE. IT IS UNCLEAR WHAT IS CAUSING THE BRACKETS TO CRACK AND/OR BREAK AT THIS TIME. ALSO THERE CURRENTLY IS NO NDT REQUIREMENT IN THE OVERHAUL OR INTERIM INSPECTION CRITERIA FOR THIS PARTICULAR PART NUMBER OF BRAKE CALIPER.

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