Partial analysis of 2014 aircraft EWIS failure rates

Periodically, Lectromec reviews the state of the industry and EWIS failure rates. It is unfortunate that the FAA no longer releases these alerts. However, the FAA still provides a wealth of information on system failures as part of their service difficultly report database (SDR). Lectromec has compiled a list of additional failure database sources.

Data Source

The following information was gathered during a recent assessment of EWIS component failures reported in the FAA service difficultly report database. The data presented here focuses on the January – November data in the SDR database as of November 16, 2014 for incidents reported to have occurred during 2014.

Before taking too much from the information presented here, it is important to note that no effort was made to normalize the data to the number of aircraft in each segment.

Some of Lectromec’s conclusions from the data review:

1. One would typically anticipate a high number of failures at the beginning and end of an aircraft’s life cycle, but incidents for aircraft with less than 10k hours represent only 7% of all reported incidents. Additional information on component life cycle can be found in the Wire Failure and Wire Component Lifecycle article.
2. Many of the aircraft individually reviewed in the 30 – 40k cycle range were 8 – 10 years old with about 10k cycles. The date of aircraft entering service is not readily available with the data (to be included in future data reviews). If this assumption holds, then most wire incidents occur around the time of the first aircraft D-check.
3. The most common system to be reported is the emergency path lighting system.
4. Many of the EWIS errors were found during routine service checks. The hazard of these EWIS failures to the aircraft/crew is not easily ascertained from many of the reports.
5. Of the 725 records reviewed:
   • 25 reports identified shorting,
   • 15 reports including detection of smoke – 8 of these were identified as faulty smoke detectors, and
   • 5 reports including mention of electrical arcing.
6. There were some reported incidents that included smoke/fire. An example of this is the following:

During landing the f/a [flight attendant] reported that when she turned on the cabin lights for landing, smoke developed out of the front ceiling vents along with a strong electrical odor. The f/a deactiveated the cabin lights and the smoke and the smoke and odor went away. The acft [aircraft] landed without incident, where maintenance r&r the light harness above the windscreen, operationally tested with no defects, and the acft was approved for return to service. [SDR Tracking number ASOA20140904114]

An interesting detail included in a service difficulty report:

Seats 7D & 7G entertainment sys inoperative with smoke & burn smell. Found harness rd-km6480-2323 & rd-km6453-0808 shorted on seat 7H. Disconnected & stowed both harness, seat 7g operations normal, no time to replace harness. [SDR Tracking number CALA2014081191929]

As the entertainment system is a non-critical system, capping and stowing the harnesses before flight is acceptable as long as failure has been addressed and no additional failure is possible at the location.

Latest Updates

Lectromec published a white paper on the 2016 EWIS failure rates. Download your copy here.