Originally Posted by
JayDee
PT2:
How it Works
The most common process for AA to go about determining how to modify one of its fleets is to write an Engineering Change Order (ECO). An ECO is the authority to make a change and provides the method of making the change. AA technical writers compose the ECOs, which then have to be approved by the engineers.
AA mechanics are inspecting direction of retention clips and lacing cords on wire bundle in MD-80 wheel wells
Due to AA's FAA certification, which is the same as all other large airlines, American's engineers have the ability to implement ECOs after they are approved internally.
While this is the given process for making changes to American's fleets, it can also leave room for interpretation to be made as to the best way to write an ECO and accomplish compliance with a given AD for AA's specific aircraft configurations.
The issue with the company's MD-80 fleet surrounds questions raised by the FAA about the way in which American implemented this particular ECO addressing the auxiliary pump wiring AD. AA had completed the ECO within the AD specified timeframe, but there was a need to change the way in which the company complied with the AA ECO regarding such items as the spacing of the ties on the wiring bundles and the direction the retention clips and lacing cords.
Thanks to the hard work of American's employees, this process is taking place safely and is being handled as quickly as possible. While it has been a disruption to AA's normal operations, the actions recognize the need to ensure that the MD-80 fleet is in complete compliance with the AD, with the goal of restoring AA's MD-80 back to service as soon as possible.
I dunno if anyone actually wanted to see this, but i found it interesting.
A little more info on how the AD/ECO/SB thing works:
The AD (2006-15-15) that is giving AA so much grief requires the incorporation of Boeing Service Bulletin MD80-29A070 which requires inspection and/or modification of the wire bundle to the auxiliary hydraulic pump in the main wheel well. Any deviations to the SB require an Alternate Means of Compliance (AMOC) issued by the FAA. AMOCs can be issued for something major such as an extension of the compliance time or very minor such as a change in the spacing of the ties on the wire bundle. Getting an AMOC can be time consuming and approval by the FAA is not automatic.
ECOs for AD compliance is basically a copy of the SB required by the AD. The airline engineer doesn't get an opportunity to do much engineering here. No improvising, ad-libbing, or changes allowed unless you have an AMOC. If the SB says to put the wire bundle ties at 1-inch intervals and the mechanic put them at 7/8-inch intervals, an enthusiastic FAA inspector can ground the airplance since you are not in compliance with the AD and therefore the airplane is not airworthy. Game over.