The following are examples of a FAA Wire Incidents Report.These are the wire incidents reported in the FAA’s February 2009 Advisory Circular 43-16A – Alert Number 367.
Incident # 1
- Aircraft Make: Aerospace Technology
- Aircraft Model: ATR42*
- Part Name: Wire Harness
- Part Condition: Damaged
- Part Location: Engine
- The engine experienced repeated events of torque fluctuations between the 20th and 24th of October for which troubleshooting had been done. On Oct. 27, the problem re-appeared and was accompanied by no response to throttle movements. The engine was shutdown and re-started in manual mode with no further problems till the flight ended. Further troubleshooting led to the replacement of the fuel control and engine wiring harness, which have been sent for investigation. Mfg will continue investigating the event and advise of root cause once established.
Incident # 2
- Aircraft Make: Beechcraft
- Aircraft Model: 58
- Part Name: Tube
- Part Condition: Chafed
- Part Location: Feathering System
- A hole was chafed in the right propeller unfeathering accumulator tube by the nr6 cylinder head temperature wire. Both the tube and wire need to be separated and secured to prevent contact.
Incident # 3
- Aircraft Make: Cessna
- Aircraft Model: 172K
- Part Name: Switch
- Part Condition: Overheated
- Part Location: Landing Light
- Landing light switch may be original (8865 hrs) detents became “sticky” and not as positive as normal. Switch function did not fail. Inspection revealed power supply wire end and lug on switch overheated. Disassy showed lug contact rivet deteriorated as well as mycarta type board material disintegrating due to heat damage around the rivet. Mfg requires newer style (1970 and newer) landing light switches to be replaced every 5 years this older style switch though likely able to carry more current should be inspected visually annually to determine if overheating is an issue.
Incident # 4
- Aircraft Make: Cessna
- Aircraft Model: 402B
- Part Name: Spar
- Part Condition: Cracked
- Part Location: LT Wing
- During routine inspection, cracks were observed in the left auxilary spar. The main gear is attached at the otbd end. The cracks were at the 11, 2, 5 and 7 o’clock positions of the hole which the wire bundle passes through, and were of varying length. Cracks were also at the 7 and 5 o’clock positions of the large access hole to which a cover plate is attached with a ring and nut plates of the opposite side. These cracks went through the screw holes and extended up to 1.5 inch. The cracks were observed 1600 hours after the main spar cap modifications. Similar cracks of varying degree have been observed in 5 of 8 acft. All have the mod. It is not known if there is any correlation.
Incident # 5
- Aircraft Make: Cessna
- Aircraft Model: 402B
- Part Name: Spar
- Part Condition: Cracked
- Part Location: LT Wing
- During routine inspection, cracks were observed in the left auxiliary spar. The main gear is attached at the otbd end. The cracks were at the 11,2,5 and 7 o’clock positions of the hole which the wire bundle passes through, and were of varying length. Cracks were also at the 7 o’clock positions of the large access hole to which a cover plate is attached with a ring and nut plates on the opposite side. This crack went through the screw hole and extended 1 inch. The cracks were observed 930 hours after the main spar cap modification. Similar cracks of varying degree have been observed in 5 of 8 acft. All have the mod. It is not know if there is any correlation.
Incident # 6
- Aircraft Make: Cirrus
- Aircraft Model: SR22
- Part Name: Wire Harness
- Part Condition: Chafed
- Part Location: Engine Compartment
- Found the black plastic wire loom that houses the map wiring harness fwd of the baffle to have chafed through the wire insulation of the wires in several locations. This is caused by the wire harness being able to move inside the loom and the loom being made from a harder material than the wire insulation. Install new wire harness and remove the plastic loom. Secure wires as needed.
Incident # 7
- Aircraft Make: Bombardier
- Aircraft Model: DHC8103
- Part Name: Line
- Part Condition: Damaged
- Part Location: Alternator
- (Can) NR1 and NR2 AC generator annunciations illuminated during taxi. Upon further investigation it was found that the following discrepancy had occurred. Found wire 2421-10002filb-1 and wire 2421-2000IGI2A-1 worn through and shorted at STA YH59:00 on left wing rear spar.
Incident # 8
- Aircraft Make: Bombardier
- Aircraft Model: DHC8301
- Part Name: Wire
- Part Condition: Shorted
- Part Location: Cabin Light
- Sparks/smoke from sidewall light 1C, ballast confirmed the source. Crew dropped PSU panel to fund the source and confirm shorting of the fore/aft wires to the aft junction box. Wiring repaired.
- Some changes have been made to the reports for clarification.
This article was written by the Lectromec technical team. Aircraft wiring is our passion and we strive to make a contribution to the field by sharing our expertise through blogs, podcasts, and videos. We hope you find this information helpful. We also encourage you to submit comments and spur discussions.