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The age of your aircraft and wire systems implications

Aging Wires & Systems

A fleet age review of 16 American aircraft operators performed by Lectromec is shown below. This includes both regional and major airlines as well as shipping companies. The data is based on available FAA data for US registered aircraft.

Percentage of Fleet in Age Range
Carrier # of Aircraft Average Age 16 – 20 years 21 – 25 years 26 – 30 years
AirTran 129 9.3 0% 0% 0%
Alaska Airlines 118 9.4 9% 6% 0%
American Airlines 568 13.6 10% 24% 3%
American Eagle 245 9.8 0% 0% 0%
Chautauqua 71 10.3 0% 0% 0%
Delta 705 12.0 9% 23% 2%
ExpressJet 160 8.0 0% 0% 0%
FedEx 355 11.0 19% 7% 3%
jetBlue 165 6.7 0% 0% 0%
Piedmont 44 15.4 9% 27% 14%
Pinnacle 140 8.9 0% 0% 0%
SkyWest 262 7.8 2% 0% 0%
Southwest 537 11.0 17% 8% 1%
United 355 14.3 19% 20% 0%
UPS 223 11.8 22% 9% 2%
US Airways 321 10.5 8% 7% 1%

Across this subsection of the aircraft surveyed, the average age is a little more than 117 years. Furthermore, it appears as though aircraft are generally phased out of service once they reach their mid-twenties; only a few operators continue to operate these aircraft beyond this limit.

This raises two questions. First, are the modern aircraft being developed today going to push the operational limit of these aircraft beyond 25 years? Second, will maintenance practices and diagnostic technologies improve, so that they can be used in maintaining aircraft airworthiness?

In response to the second questions, aircraft do go through multiple levels of maintenance on regular intervals. Commercial aircraft typically follow a four stage maintenance plan (for more information, check out the Wikipedia entry). The frequency of the maintenance actions are broken down as follows (the more infrequent a maintenance check, the more invasive):

Level Frequency
A Check Every 500 – 800 flight hours
B Check Every 4 – 6 months
C Check Every 15 – 21 months
D Check Every 5 years

As such, even the aged aircraft with thousands of hours of service have been thoroughly reviewed, inspected, modified, repaired, and maintained. Part of the FAA’s focus on wire systems requires that operators develop an Enhanced Zonal Assessment Program (EZAP), which creates defined procedures for wire system examination. These visual inspections are to be carried out periodically to identify wire system issues before they create system or aircraft level problems.

In the next month, we plan to review the correlation of the aging aircraft with EWIS-related service difficulty reports (SDRs) available from the FAA. The results of this analysis will be posted here.

Michael Traskos

Michael Traskos

President, Lectromec

Michael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components.