Accident Details
On July 27, 2023, at approximately 1441 eastern daylight time, a Piper PA-28-180 (registration N15417) sustained substantial damage during an accident near Knoxville, Tennessee. The aircraft was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor and student pilot were not injured.
Flight Sequence
The flight instructor reported that the accident flight was the student pilot's first flight, a discovery flight. The preflight inspection, engine start, taxi, and run-up were normal. The instructor initiated a takeoff roll on runway 26 by allowing the student pilot to advance the throttle. The engine rpm initially increased to 2,200, then decreased to 800, followed by flames emanating from the engine cowling. The instructor rejected the takeoff, advanced the throttle lever, retracted the mixture lever, and turned off all electrical equipment, including the master switch. He also instructed the student pilot to turn the magnetos and fuel selector to off, which the student did. Both occupants then exited the airplane on the runway and called the fixed base operator for assistance.
Examination Findings
An examination of the engine compartment by a Federal Aviation Administration inspector revealed substantial damage to an engine mount tube. The inspector noted that a section of starter motor electrical lead, approximately 25 to 30 inches in length, was not clamped and had drooped onto the fuel primer line. Metal "beads" were observed on top of the fuel primer line, consistent with chafing and welding due to contact from the electrical lead.
Maintenance Records
Review of maintenance records showed that the airplane had been operated for 73 hours during a one-month period following its most recent 100-hour inspection.
Applicable Guidance
FAA Advisory Circular AC 43-13-1, Section 2 Fuel Systems, states: "…b Routing. Make sure that the line does not chafe against control cables, airframe structure etc., or come in contact with electrical wiring or conduit…In no case should wiring be supported by the fuel line…" The Piper Cherokee Service Manual, Table III-I Inspection Report, B. Engine Group, includes: "…39. Inspect engine compartment wiring for condition (chafing, cracked insulation, general deterioration), security, proper routing, and correct installation…"