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On December 24, 2007, about 0750 central standard time, a Piper PA-32R Turbo Saratoga, N8158B, received minor damage due to an engine fire after departing from Pensacola Regional Airport (PNS), Pensacola, Florida. An emergency landing was accomplished at Destin-Fort Walton Beach Airport (DTS), Destin, Florida. The certificated private pilot/owner and the certificated flight instructor (CFI) were not injured. The personal flight was being operated on an instrument flight rules flight plan under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed in the area at the time of the incident.
The flight departed PNS about 0725, and was cleared to climb to and maintain 11,000 feet by air traffic control (ATC). At approximately 10,000 feet both pilots noticed the engine "stumble," which they described as similar to, but lasting longer than, a "miss." The pilots acknowledged the event to one another, but neither one knew what caused it. Seconds later, they smelled, and then saw, smoke emanating from the windshield defroster ducts. The CFI then instructed the pilot to conduct an emergency descent. The pilot reduced the power and pushed the nose over. Concurrent with the pushover, the smoke disappeared, but the engine was running roughly. The CFI asked ATC for the closest airport, and he selected DTS from the choices provided by ATC, since he was familiar with that airport.
During the emergency descent, the pilot continued to fly the airplane, while the CFI handled the communications. DTS is a non-towered airport. The pilot flew an abbreviated traffic pattern and made an uneventful landing. He taxied to the closest ramp, and shut down the airplane. After exiting the airplane, the pilots noted external fire damage, but no active fire. The CFI estimated that approximately 5 minutes passed from the time that the smoke was noticed, until the time that the airplane landed.
The instrument student, seated in the left seat, held a private pilot certificate with an airplane single-engine land rating. He had approximately 367 total hours of flight experience, including approximately 198 hours in the incident airplane make and model. His most recent flight review was accomplished in October 2006, and his most recent Federal Aviation Administration (FAA) second-class medical certificate was issued in October 2007.
The CFI, seated in the right seat, held a commercial pilot certificate with airplane single engine land, multi engine land, and rotorcraft helicopter ratings; and a flight instructor certificate with airplane single engine, rotorcraft helicopter, and instrument airplane ratings. The CFI reported 1,219 total hours of flight experience, including 944 hours in single engine airplanes, and 26 in the incident airplane make and model. His most recent flight review was accomplished in November 2006, and his most recent FAA first-class medical certificate was issued in July 2007.
According to the maintenance records, the most recent annual inspection entry was dated September 20, 2007. The records indicated an airplane total time of 4,383 hours, and an engine time since major overhaul (SMOH) of 1,343 hours. As of the date of the incident, the airplane had accumulated a total of 4,441 hours time in service, and 59 hours since the last annual inspection.
The airplane was equipped with a Lycoming TIO-540-S1AD engine. As of the date of the incident, the engine had accumulated approximately 1,401 hours since major overhaul (SMOH), and 50 hours since the most recent maintenance activity on the fuel system. The fuel system maintenance records entry, dated October 18, 2007, stated in part "Reinstalled fuel system...& six injectors after repair." The entry cited Lycoming service bulletin "342D" as one reference document for the maintenance.
The 0753 automated weather observation at DTS recorded winds from 200 degrees at 7 knots, with gusts to 15 knots, clear skies, temperature 6 degrees Celsius (C), dew point minus 3 degrees C, and an altimeter setting of 30.25 inches of mercury.
WRECKAGE AND IMPACT INFORMATION
Thermal damage was observed on the aft right cowl, the right underside of the fuselage, and the aft, upper right portion of the engine compartment. The cowl, fuselage and engine compartment damage included scorched paint, distressed sheet metal and other thermal damage. Some sheet metal had been consumed by the fire. The majority of the hoses, cables, wires and wire bundles in the engine compartment were shrouded with aftermarket heat-protective "fire sleeves." Several of the sleeves exhibited significant charring and other thermal effects. All sleeved wires, cables and hoses remained intact and functional.
Examination of the engine compartment revealed that the fuel injector line to the No. 5 cylinder, which was the aft-most of the right cylinder bank, had fractured and separated. The separation point was approximately 1/4 inch from the end of the fuel line at the fuel injector end. The two line segments and associated components were removed and sent to the National Transportation Safety Board Materials Laboratory in Washington D.C., for further analysis.
Lycoming Service Bulletins
Lycoming Service Bulletin (SB) 342D provided installation and inspection details for the fuel injector lines and associated clamps. On March 18, 2004 Lycoming issued Mandatory Service Bulletin (SB) 342E, which superseded SB 342D with the inclusion of additional engine models.
Lycoming SB 342E variously specified a minimum radius curve of the fuel line adjacent to the injector end as "0.62" and "5/8" inches. For reference purposes, 0.625 is the decimal equivalent of 5/8. Lycoming SB 342E also specified a minimum distance of 0.7 inch between the end of the ferrule and the start of the curve in the line.
Paragraph 2 of Lycoming SB 342E contained the following statements regarding repair and replacement of the fuel lines. "Remove any line that appears faulty. Do not attempt to repair a line that leaks...any line with an inside radius less than 5/8 inch must be replaced." It specified technicians to "Also inspect solder joints at end of lines for cracks. Replace cracked lines, they cannot be repaired."
The Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 2002-26-01, effective January 3, 2003, which was applicable to this engine. AD 2002-26-01 superseded AD 93-05-22, which was issued in 1993. Both ADs mandated initial and recurrent inspections of the fuel injector lines. The compliance times required by AD 2002-26-01 were "every 100 hours, annual inspection, overhaul and any time fuel lines or clamps are serviced, removed or replaced."
Fuel Line Configuration
According to Diagram 25 in Lycoming Service Bulletin 342E, the fractured fuel line was component number "8," which was listed as a "TUBE ASSY...Manifold to nozzle fuel line," part number (p/n) LW-12098-0-100. This part consisted of a 1/8 inch diameter stainless steel tube, with a scarf-cut ferrule brazed onto each end. One ferrule mated to the fuel injector, and the other mated to the fuel distribution manifold.
Safety Board Materials Laboratory Examination
The fractured fuel line was examined by Safety Board Materials Laboratory personnel, and the laboratory report is available under separate cover in the incident docket. The examination revealed that the ferrule and approximately 1/2 inch of the fuel line adjacent to the fracture were darkened and discolored consistent with localized exposure to high temperatures. The manifold end of the line was not discolored. Adjacent to the injector end, the fuel line was bent into a smooth curve that measured 0.49 inch in radius. The fractured fuel line measured approximately 0.7 inch from the end of the ferrule to the beginning of the curve.
The fuel line was fractured at the brazed joint within the scarf-cut end of the ferrule. Copper colored filler brazing metal was present on the exterior surfaces of the fuel line on both sides of the fracture. Optical and scanning electron microscope (SEM) inspections of the fracture surfaces revealed features indicative of fatigue progression, with multiple fatigue initiation sites on the exterior of the fuel line. The fatigue penetrated radially through the wall of the fuel line, and then spread circumferentially in both directions around the fuel line.
The brazed joint at the fractured end of the fuel line was rough, and the braze filler metal was formed into clumps. In contrast, the brazed joint at the intact end of the fuel line was smooth, and formed an even transition from the ferrule to the fuel line. Braze metal was visible in the interior of the fuel line at the fractured end, but no braze filler metal was visible inside the intact end of the fuel line.
Energy dispersive x-ray spectra (EDS) acquired during SEM examinations were consistent with a 300 series chromium, nickel stainless steel material for the fuel line, and identified the braze filler material at the fractured end as predominately copper, with a significant amount of silver. EDS spectra of the intact braze filler metal on the opposite end revealed peaks for silver, copper, zinc and cadmium, which was similar to the aerospace materials specification for braze filler metal.