Date: 201501
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Main Gear
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Confusion; Time Pressure; Workload
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Maintenance Action
Contributing factors: Chart Or Publication; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was assigned to work on securing the RH main landing gear side stay bushing Task Card with an Engineering Change/Repair Authorization (EC/RA). I; Mechanic X; was directed by my Lead Mechanic to work with Mechanics Y and Z. Lead Mechanic handed me the task card with EC/RA attached just before our afternoon break. I placed the paperwork in my toolbox and locked it; then went to break. Immediately after break; Lead Mechanic met with myself and Mechanics Y and Z to discuss the job. Lead Mechanic told us that the new retaining nut and washer were on order and should be delivered within minutes; and to go ahead and set up for installation. At that time; we briefly went over the paperwork for this phase; and the Lead Mechanic told us the torque was 500 foot pounds. While I ordered the sealant as required; Mechanic Y went to the hangar to obtain the torque wrench for this operation. Upon his return; I set the tooling in place; put the nut and locking tab washer in place; spun it down by hand; and then engaged the tooling to begin the final torquing of the retaining nut. Mechanic Y read off to Mechanic Z that the final torque setting was 500 foot pounds and that the initial torque setting was 440 foot pounds. Mechanic Z then set the torque wrench to 440 foot pounds; showed the setting to our inspector; and then attached the wrench to the tooling. I held the tooling in place while Mechanic Y and Mechanic Z applied the torque to the retaining nut. Once the initial torque was reached; we checked the tab lock positions (myself and our inspector); and it was necessary to advance the position of the retaining nut by close to 1/4 inch to align the lock tab. Once we reached 500 foot pounds; the tab lock was still not aligned. The inspector instructed us to back the collar off; and then reapply the minimum torque of 440 foot pounds; and recheck the tab lock position. We continued this through four break/reset sequences with no better luck. Mechanics Y and Z and myself went to see the incoming midnight supervisor; and explained the dilemma. He took the paperwork and briefly perused it; then said that we should turn the issue over to the incoming crew. We turned the paperwork over to Mechanic A; an Aircraft Maintenance Technician (AMT) on midnight shift; and explained what problem we were having. Mechanic A left our presence with the paperwork; and then returned to me approximately 15 minutes later to show me that he read (after struggling with the interpretation) that the applied torque was to be no more than 500 INCH pounds. The paperwork as written (exactly) showed '500 lbf. in'; in the text. By this misinterpretation; the applied torque was 12 times greater than was intended in the operation.

Callback: Reporter stated there is a difference between Airbus and Boeing in the way maintenance information is presented to mechanics. References noting foot pounds and inch pounds are simpler and more clear-cut with Boeing Manuals. Boeing uses LB/FT for Foot pounds and LB/In for Inch pounds; whereas Airbus will reference Foot pounds Force with LBF-Ft and Inch pounds with LBF-In. Their Job Cards have the same information as the Airbus Aircraft Maintenance Manuals (AMMs); but in their situation; no diagrams/pictorials were included due to Airbus having sent the special tooling directly to Maintenance.  Most mechanics take about a year to learn how to use Airbus AMMs and not get themselves into too much trouble due to misinterpretation of the information they are reading. But; as his report shows; even experienced technicians still mis-read Job Cards.



Synopsis: An Aircraft Maintenance Technician reports how misinterpretation of an A320 Job Card reference note contributed to a right-hand main landing gear side stay bushing retaining nut final torque being twelve times greater than specified. Technician also noted the differences in how information is presented to AMTs using Boeing or Airbus Aircraft Maintenance Manuals.