Maintenance personnel reported that the engine mounts on a boeing 757 were over-torqued because the ...

Narrative:

During performance of engineering order (east.O) of a B757 on left engine; there was a discovery of torque variance between forward engine mount bolts ending in -1; -2 [as] opposed to the -3. Members of the facility's engine change crew recognized torque difference between the aircraft maintenance manual (amm); called out in [the] east.O; and our normal engine change paperwork job card by nearly 100 feet lbs. Of torque. Then searched local inventory found all bolts in stock were -3. Proceeded to verify all stock in company were -3 to include; a scenario of ordering a -1/ -2 changes to a -3 in the system. The inspector went to verify bolts installed in engine by taking a picture of 1 out of the 4 bolts. He saw a line of numerals that appeared to be part numbers ending in the numeral 3 then a substantial space. He verified with another mechanic if he concurred it being a -3 bolt. We proceeded with full confidence; that -3 bolts were installed. Due to [the] generation of [a different] east.O; next base maintenance removed and replaced left forward engine mount bolts and barrel nuts; discovering that the bolts installed were indeed-2 bolts and incorrectly identified by inspector as a -3; subsequently realizing the bolts were over torqued.

Original NASA ASRS Text

Title: Maintenance personnel reported that the engine mounts on a Boeing 757 were over-torqued because the part number of the mount bolts were incorrect.

Narrative: During performance of Engineering Order (E.O) of a B757 on left Engine; there was a discovery of torque variance between Forward Engine Mount Bolts ending in -1; -2 [as] opposed to the -3. Members of the facility's engine change crew recognized torque difference between the Aircraft Maintenance Manual (AMM); called out in [the] E.O; and our normal engine change paperwork job card by nearly 100 feet lbs. of torque. Then searched local inventory found all bolts in stock were -3. Proceeded to verify all stock in company were -3 to include; a scenario of ordering a -1/ -2 changes to a -3 in the system. The inspector went to verify bolts installed in engine by taking a picture of 1 out of the 4 bolts. He saw a line of numerals that appeared to be Part Numbers ending in the numeral 3 then a substantial space. He verified with another mechanic if he concurred it being a -3 bolt. We proceeded with full confidence; that -3 bolts were installed. Due to [the] generation of [a different] E.O; next base maintenance removed and replaced Left Forward Engine Mount bolts and barrel nuts; discovering that the bolts installed were indeed-2 bolts and incorrectly identified by inspector as a -3; subsequently realizing the bolts were over torqued.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1515127
Time
Date	201801
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Powerplant Mounting
Person 1
Function	Technician
Person 2
Function	Technician
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

Maintenance personnel reported that the engine mounts on a boeing 757 were over-torqued because the part number of the mount bolts were incorrect.