Allows "Dual Maintenance" In Limited Circumstances

They aren't big changes... but the FAA has already tweaked its ruling on Extended Operations (ETOPS) regulations for Part 121 and Part 135 turbine transport aircraft, one month after the original rule was published.

The changes -- none of which are substantive, in the FAA's words -- correct the rule language applicable to dual maintenance and formatting of a Part 1 definition and section of Appendix G. Following publication of the final rule, it was brought to the attention of the FAA the original intent of the concept of "dual maintenance" in the final rule did not codify existing FAA ETOPS guidance, as published in the notice of proposed rulemaking.

The amendment clarifies that language.

"Dual maintenance" is a concept relating to repetition of maintenance errors on redundant systems -- i.e., when one mechanic performs the same error while repairing two or more systems on the same aircraft. An example of dual maintenance error is failing to install o-rings on engine oil or fuel components on multiple engines.

Establishing procedures to avoid dual maintenance can minimize the probability of such errors. The use of two or more mechanics reduces the risk of this type of error. Routine tasks on multiple similar elements, such as oil and fuel filter changes, should never be scheduled and assigned on the same maintenance visit.

However, the FAA states, in some cases such procedures may be unavoidable. For instance, a pilot's report of a discrepancy on an ETOPS significant system may require maintenance on one engine, while a scheduled maintenance event is performed on the other engine.

In such cases, the certificate holder must establish and follow procedures to mitigate the risk of human error, according to the FAA's new language.

ETOPS regulations allow aircraft, other than an all-cargo operation in an airplane with more than two engines, to operate on one engine in the event of emergency within a time threshold identified in part 121 or part 135. That time threshold is determined using an approved one-engine-inoperative cruise speed under standard atmospheric conditions in still air.

FMI: Read The Amendment (.pdf)