History of Flight
On July 19, 2015, at about 1320 Pacific daylight time, a Piper PA-28-181, registration N8740E, collided with terrain minutes after departing Henderson Executive Airport in Las Vegas, Nevada. The private pilot and three passengers were seriously injured, and the airplane was destroyed by a postaccident fire. The flight, operating under 14 CFR Part 91 as a personal flight, had originated from Las Vegas about 1330 and was destined for San Diego, California. Visual meteorological conditions prevailed, and no flight plan had been filed.
The pilot reported that the takeoff seemed normal but that the airplane's climb was "sluggish" after becoming airborne, with engine rpm 200-300 lower than normal. He was able to maintain straight and level flight at about 300 feet above ground level. When the pilot initiated a left-hand turn to return to the airport, the airplane immediately began to lose altitude. He selected a landing site and executed a forced landing into an open area associated with a construction site. During the landing sequence into uneven terrain, the landing gear was torn off, and the airplane caught fire. After the airplane came to rest, the front passenger door was opened and the occupants evacuated. The airplane was consumed by the postaccident fire.
The tower controller at Henderson Airport reported that the airplane appeared to not be climbing normally after takeoff, and he cleared the pilot to make any maneuvers necessary to return to the airport. A witness observed the airplane takeoff and struggle to gain altitude; it then made a left turn followed by a steep bank turn and crashed. The witness noted that the occupants egressed the airplane before it was completely engulfed in fire.
Aircraft Information
The airplane was a Piper PA-28-181, serial number unknown, with an empty weight of 1,502.5 lbs and a maximum gross weight of 2,550 lbs. The pilot reported having 30 gallons (180 lbs) of fuel onboard at takeoff, and the estimated combined weight of the occupants was 770 lbs. The calculated takeoff weight was 2,452.5 lbs. The airport elevation is 2,492 ft mean sea level, the temperature was 33°C, and the pressure altitude was 30.10 inHg, yielding a density altitude of 5,014 ft. Using the climb performance chart for the PA-28-181, the expected rate of climb under those conditions was 520 feet per minute.
A review of the airplane's maintenance records showed that the most recent annual inspection was performed on February 25, 2015, at a total airframe time of 4,040 hours. The mechanic who performed the inspection noted in the airframe logbook that the carburetor heat control bracket required repair and that the number 2 navigation radio head required a placard indicating it was inoperative. After those repairs were completed by an A&P mechanic, the entry stated, "this aircraft will be airworthy & ok for return to service." The mechanic later told the NTSB investigator-in-charge that he performed an engine static rpm check during the annual inspection and observed that the rpm was 10% to 20% below normal. He attributed this to a loose carburetor heat door, which could allow the carb heat to be in an unknown position. Maintenance records from First Flight Corp in San Diego, California, documented that the carburetor heat bracket was repaired on March 5, 2015.
The engine, a Lycoming O-360-A4A producing 180 hp, was overhauled on October 6, 1986, and had accumulated 1,461 hours since overhaul. The airplane and engine had accumulated about 150.4 hours over the 10 years preceding the accident.
Engine Examination
On July 23, 2015, the engine was examined by a Lycoming technical representative under FAA oversight. The top spark plugs were removed and examined. The crankshaft was rotated by hand and was free and easy to rotate in both directions. “Thumb” compression was observed in proper order on all four cylinders, and the valve train operated in proper order. Clean, uncontaminated oil was present at all four rocker box areas. Investigators noted that each intake valve rocker exhibited limited movement, estimated to be about 50% less than normal. Since intake valves of opposing cylinders share a common cam lobe, investigators drilled holes through the top of the engine case to insert a lighted borescope. Visual examination confirmed excessive wear on the intake cam lobes. Mechanical continuity was established throughout the rotating group, valve train, and accessory section during hand rotation.
The bottom spark plugs were not removed. Combustion chambers examined through the spark plug holes showed no mechanical damage, foreign object ingestion, or detonation. Valves were intact and undamaged, with no evidence of valve-to-piston contact.
The left and right magnetos remained clamped at their mounting pads but had sustained thermal damage from the post-impact ground fire. The ignition harness was secure. The magnetos could not be functionally tested due to thermal damage, and magneto-to-engine timing could not be ascertained.
No oil residue was found in the exhaust system gas path. Exhaust system components exhibited ductile bending but were free of obstructions.
A teardown examination of the engine was conducted on September 1, 2015, under NTSB oversight. The engine was completely disassembled. Cylinder combustion chambers and barrels were mechanically undamaged, with no evidence of foreign object ingestion or detonation. Valves were intact. Pistons were intact, and ring assemblies were free to rotate. Mechanical continuity of the rotating group was confirmed. Accessory gears, including the crankshaft gear, bolt, and dowel, were intact and showed no pre-impact malfunction. No evidence of lubrication deprivation was found. The crankshaft and connecting rods were free of heat distress. The valve tappet faces exhibited significant spalling damage.
Additional Information
Lycoming Engines Mandatory Service Bulletin SB301B, dated February 18, 1977, provides guidance for maintenance procedures and service limitations for valves. Paragraph 1(b) states, "Rotate the engine by hand and check to determine that all cylinders have normal lift and that rocker arms operate normally," with a 400-hour inspection interval. The airplane's logbooks contained no record of a camshaft lobe inspection, camshaft replacement, or compliance with this service bulletin.
According to Lycoming Engines Service Instruction SI1009AW, the engine should be overhauled at 2,000-hour intervals or before the twelfth year, whichever occurs first.