History of Flight
On October 21, 2018, about 1200 mountain daylight time, a Piper PA46-350P, N413LL, was substantially damaged during an accident near Hurricane, Utah. The airline transport pilot and one passenger suffered serious injuries, while the other three passengers were uninjured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The pilot reported an uneventful preflight, engine runup, and takeoff from Runway 1. After retracting the landing gear and initiating a left turn to 340°, he climbed to about 1,000 ft above ground level (agl) when he detected a smoke smell. The odor rapidly intensified, and the hydraulic pump annunciator illuminated. Suspecting the hydraulic pump, the pilot selected the gear down lever to deactivate it. A few seconds later, the main gear extension lights illuminated, but no nose gear indication appeared.
While turning back to the airport, the engine emitted a loud noise, oil pressure dropped to zero, and all engine power was lost. The pilot calculated he could not glide to the runway and began searching for an alternate landing site. Smoke hindered his visibility; he saw only houses, hills, and gullies. At about 400 ft agl, he spotted a small plowed field to the right. After touchdown, the airplane struck a metal fence and irrigation pipe. The right wing separated, and the airplane slid approximately 125 ft before stopping. All occupants exited through the upper section of the rear left cabin door. Once outside, the pilot observed a fire erupting from the engine cowling. The local fire department arrived shortly and extinguished the fire before it reached the cabin.
Wreckage and Impact Information
Post-accident examination revealed fire damage limited to the roof and forward baggage compartment, as well as the engine accessory area between the firewall and aft air baffles. Soot and splatter marks trailed aft from two holes in the right fuselage at the firewall; elsewhere, soot marks traveled upward.
Inside the engine compartment, thermal damage forward of the baffles was confined to charred magneto wires and the fire sleeve of the fuel flow divider inlet line. Turbocharger clamps were intact, and both turbochargers were undamaged. The oil dipstick indicated about 10.5 quarts of oil, with no signs of crankcase perforation or catastrophic engine failure. Fuel, oil, hydraulic, and upper deck pressure lines had thermal damage but remained secure at their fittings.
Thermal damage was more severe in the right accessory area, consuming cabin climate scat tubes, vacuum lines, and the oil pressure sender housing. The right intercooler inlet pipe assembly displayed orange discoloration with a lateral flow pattern. The firewall exhibited yellow-blue thermal discoloration over most of its surface, transitioning to orange on the upper right side.
The fuel line from the fuel injection servo to the fuel flow divider passed next to the exhaust pipe crossover tube heat shield on the right side. Its fire sleeve was charred along most of its length, with heavier thermal damage near the heat shield. Disassembly revealed that the exhaust crossover pipe assembly appeared misaligned at the right slip joint. Orange/yellow discoloration surrounded the pipe joint, and similar discoloration on the inner heat shield surface showed a swirling form leading to a lateral flow pattern to the right. The crossover pipe hardware and support brackets were secure, with no evidence of impact damage.
Maintenance Findings
Lycoming Service Bulletin (SB) 521, issued February 1995, required annual or 250-hour inspections of exhaust system slip and flange joints to identify misaligned components that could lead to exhaust gas escape. The SB specified that the right pipe should engage the slip joint with a 3/4-inch overlap. Examination disclosed that the right pipe had only about 1/16-inch engagement on its forward side and 3/16-inch on the rear.
The last maintenance event occurred on October 2, 2018, 7.5 flight hours before the accident. At that time, the engine-driven fuel pump was replaced, and SB 521 was performed, resulting in replacement of the intermediate and left crossover pipes and the forward heat shield insert. The mechanic stated that the crossover pipes were replaced because two had bound together.
The SB outlined reinstallation steps including marking the pipes with a non-graphite marker to confirm the 3/4-inch penetration of the right pipe into the intermediate pipe sleeve. The mechanic reported that he instead used anti-seize compound to judge depth by the mark it left, and did not use a marker. Access to the pipes was very limited at the rear of the engine, requiring opening the triangular baggage access panel for alignment. He stated it took three attempts to align the pipe properly before securing the assembly and installing the heat shield. He had performed this task twice before on similar aircraft, about a year prior.
The Chief Inspector of the maintenance facility inspected the work. He stated that with the heat shield in place, he could not confirm the pipe overlap. He considered using anti-seize compound to gauge overlap standard practice and trusted the mechanic. To check for leaks, he reached through the baggage access panel and pulled the tubes to ensure they were secure. He also started the engine and again reached in to feel for any exhaust "blow-by," confirming none was detected.