Aviation Accident Summaries

Aviation Accident Summary LAX06FA082

Mammoth Lakes, CA, USA

Aircraft #1

N9124W

Piper PA-28-235

Analysis

The airplane rolled right and collided with terrain during the initial climb after takeoff. A surviving passenger said that the takeoff and initial climb rate seemed normal. The passenger reported that about 1 1/2 to 2 minutes into the flight, the airplane, unexpectedly and without warning, went hard right and pitched straight down into the ground. Ground witnesses said that the airplane was 150 to 200 feet above the ground, and did not appear to gain any additional altitude. One witness, on an access road just north of the airport, had a profile view of the airplane during the majority of the accident sequence. He reported an "excessive" angle of attack on the takeoff. He saw the nose pitch down, and thought the airplane was about 100 feet above the ground. The witness then saw the nose pitch up again, increasing the angle of attack. The pitch attitude was steep; the witness said he was able to see the tops of the wings. He stated that the airplane flew straight ahead under controlled conditions, but appeared to be "mushing" through the air. He lost sight of the airplane as he rounded a bend in the road. When he saw the airplane again it was in a left descending spiral. Investigators found no anomalies that would have precluded normal operation of the airframe or engine.

Factual Information

HISTORY OF FLIGHT On January 8, 2006, about 1430 Pacific standard time, a Piper PA-28-235, N9124W, impacted flat, level terrain shortly after takeoff from runway 9, about 1.5 miles northwest of Mammoth Yosemite Airport (MMH), Mammoth Lakes, California. The pilot/owner operated the airplane under the provisions of 14 CFR Part 91 as a personal cross-country flight. The airplane was destroyed. The private pilot and one passenger were fatally injured, and one passenger received serious injuries. Visual meteorological conditions prevailed for the flight, and no flight plan had been filed. The flight was destined for San Luis County Regional Airport (SBP), San Luis Obispo, California. The wreckage was located at global positioning system (GPS) coordinates 37 degrees 37.955 minutes north latitude and 118 degrees 53.961 minutes west longitude. The Airport/ Facility Directory, Southwest U. S., indicated Mammoth Yosemite Airport (MMH) runway 9/27 was 7,000 feet long and 100 feet wide. The runway surface was composed of asphalt. The airport elevation was 7,128 feet mean sea level. According to witnesses, the airplane used most of the runway during the takeoff roll. Once airborne, witnesses indicated that the airplane was 150 to 200 feet above the ground, and did not appear to gain any additional altitude. One witness, on an access road just north of the airport, had a profile view of the airplane during the majority of the accident sequence. He reported an "excessive" angle of attack on the takeoff. He saw the nose pitch down, and thought the airplane was about 100 feet above the ground. The witness then saw the nose pitch up again, increasing the angle of attack. The pitch attitude was steep; the witness was able to see the tops of the wings. He stated that the airplane flew straight ahead under controlled conditions, but appeared to be "mushing" through the air. He lost sight of the airplane as he rounded a bend in the road. When he saw the airplane again it was in a left descending spiral. He reported cool temperatures, but not freezing, clear skies, and variable wind conditions at 3 knots. Another witness traveling on Highway 395 indicated that he was viewing the airplane from behind. He indicated that the airplane did not seem to be climbing "very well," but was under control. The airplane drifted over the highway, the right wing dropped, then the nose dropped and the next thing he saw was a big snow cloud. To him, the airplane appeared to hang in the air. From his perspective the airplane was never any higher than 200 feet above the ground. He indicated that it was a beautiful day, clear skies, and no wind. The survivor in the right rear seat had flown several times in the airplane with the pilot to and from Mammoth. He stated that he had a vivid and clear memory of events until a few seconds before impact. The weather was good. It was clear skies, a light wind, and the temperature was a little above freezing. The pilot packed the luggage in the airplane himself, which was his policy so that he could distribute the weight equally. The pilot went through his normal checks of the airplane's exterior before boarding, and checklists after boarding. The pilot did an engine run up. The engine was running normal all of the time before and after takeoff. This takeoff was like the others. The airplane used the majority of the runway to lift off. After liftoff, the airplane flew straight and normal. The survivor looked at a gauge, and noted an indication of 400 feet per minute rate of climb. This was similar to rates that he had previously observed. The pilot had informed him that the air was thinner at higher altitudes, and therefore there was less lift. About 1 1/2 to 2 minutes into the flight, the airplane was climbing at the same rate. It then, unexpectedly and without warning, went hard right and pitched straight down. The survivor estimated that the altitude was about 600 to 700 feet agl, which he felt was consistent with the rate of climb and amount of time airborne. The pilot attempted to gain control with the yoke, but nothing affected the descent. He saw the ground coming up very fast through the windshield. The survivor said that the pilot was not an aggressive flyer. He did not observe an excessive angle of attack or a pitch up, then down, and up again as the witnesses reported. In a follow-up interview, the survivor stated that he did not look at the air speed indicator while they were flying, but the air speed was normal as to what he had observed on previous flights leaving Mammoth in the winter. He did not feel that they were going abnormally fast or slow and the pilot never made any indications of a fast or slow speed while flying. In addition, there was no warning noise from the airplane of going too slow. If he heard the noise, that would have prompted him to look at the speed gauge. He remembered that the pilot checked with the airport people regarding the temperature just before leaving, which he believed was about 35 to 36 degrees. The airplane used about the same amount of runway as it had in the past, which was about 2/3 to maybe 1/2 of the runway length. As far as packing the plane, the survivor remembered that the pilot packed the left back seat with three bags on the seat, a small one on the floor (he thought that the small one contained ski boots), and his flight map bag on the floor. The pilot then secured them (he thought for his comfort in the other seat) with all of their ski coats and the front right passenger's pillow. The ski coats had many things in them and attached to them (gloves, walkie talkies, hats and the like). The seat next to him was well filled, and packed so high that he couldn't even see out of that back window on that side. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed that the pilot held a private pilot certificate with an airplane single engine land rating. He had a third-class medical certificate issued on October 26, 2004. It had the limitation that the pilot must wear corrective lenses. An examination of the pilot's logbook indicated a total flight time of 520 hours at the last entry dated July 30, 2005. AIRCRAFT INFORMATION The airplane was a Piper PA-28-235, serial number 28-10740. A review of the airplane's logbooks revealed a total airframe time of 2,832 hours at the last annual inspection. An annual inspection was completed on January 24, 2005. The tachometer read 2,832 at the last inspection. The airplane had a Textron Lycoming O-540B4B5 engine, serial number L-10687-40, installed. Time since overhaul on the engine at the last annual inspection was 539 hours. WRECKAGE AND IMPACT INFORMATION Investigators from the National Transporation Safety Board, the FAA, Piper, and Textron Lycoming examined the wreckage at the accident scene. The first identified point of contact (FIPC) was a ground scar, about 20 feet in length, which was on a magnetic bearing of 314 degrees. The fuselage came to rest inverted along a magnetic bearing of 004 degrees, and remained intact. The cabin roof crushed down and to the left. The engine remained partially attached at the firewall, but offset to the right. The nose landing gear remained partially attached, but bent towards the right side of the fuselage. The right wing separated at the root; it came to rest inverted about 10 feet from the right side of fuselage. The center section of the wing exhibited aft crush damage. At midspan, the wing bent in an upward direction (downward when turned upright). The tip tank contained several gallons of a blue fluid. The main fuel tank ruptured, but contained a blue colored fluid. The landing gear remained attached to the wing. The aileron bellcrank assembly separated, and pulled out of the wing. The aileron cables remained attached to the bellcrank assembly. The control limit stops were undamaged. The left wing remained attached to the fuselage. It exhibited aft crush damage outboard of the stall-warning vane. At midspan, the wing bent in an upward direction (downward when turned upright). The outboard section partially separated. Both the tip and main fuel tank contained a blue-colored fluid. The flap remained attached to the wing, and was in the retracted position. The aileron remained attached to the wing by the outboard hinge assembly, and the aileron cables remained attached to the bellcrank. The landing gear remained connected. The empennage sustained mechanical impact damage, and partially separated from the cabin near the rear baggage door. It was slightly twisted compared to the cabin area. All control surfaces remained attached, and their respective control cables remained attached to their attachment fittings. The propeller remained attached to engine crankshaft. The propeller spinner was destroyed. One propeller blade had S-bending, leading and trailing edge gouging, and chordwise scratching about 1-foot inboard from the tip. The other blade curled at the tip, had leading edge gouging, and chordwise scratching. MEDICAL AND PATHOLOGICAL INFORMATION The Mono County Coroner conducted an autopsy on the pilot on January 10, 2006. The FAA Forensic Toxicology Research Team in Oklahoma City, Oklahoma, performed a toxicological analysis, from samples obtained during the autopsy. The results of the analysis of the specimens were negative for carbon monoxide, cyanide, and volatiles. The report contained the following results: atenolol detected in blood and urine. TESTS AND RESEARCH Investigators examined the wreckage at Aircraft Recovery Service, Littlerock, California, on January 13, 2006. Investigators removed the top spark plugs. All spark plugs were clean with no mechanical deformation. The spark plug electrodes for cylinders no. 5 and 6 were discolored. A borescope inspection revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head. Investigators removed the rocker box covers, and observed no metal contamination. They manually rotated the engine. The engine rotated freely and the valves moved approximately the same amount of lift in firing order. The gears in the accessory case turned freely. Investigators obtained thumb compression on all cylinders in firing order. Investigators manually rotated the magnetos. The left magnetos produced spark at all posts. The impulse coupling functioned properly. The engine to magneto timing was 24 degrees before top dead center (BTDC). Engine to magneto timing was 25 degrees BTDC for the right magneto. Investigators did not get spark from the magneto. The manufacturer examined the magnetos at their facilities under the supervision of a Safety Board investigator. Technicians mounted the right magneto in a test fixture with a test fixture cap, and installed ignition leads. They rotated the unit, and it produced spark at all leads in the proper order, and at all rpm settings. The vacuum pump was secure at its mounting pad. The drive turned when manually rotated. The oil suction screen was clean. Investigators did not remove the oil filter. The carburetor was secure to its mounting pad. The metal floats were not crushed, and the fuel filter screen was clean. The accelerator pump discharged a stream of fluid when manually activated. The float bowl was full of a blue liquid similar in color and smell to aviation 100 low lead fuel. There were no visible contaminants or water inside. The fuel pump's rubber diaphragm was unbroken; a blue fluid was inside the pump. Investigators did not observe any contamination or obstructions. The Hartzell Propeller Governor was secure at its mounting pad. It was near the low pitch stop (high rpm). The air filter element was intact and unobstructed. The fuel selector valve's position was between the right tip and right main position. Examination of the trim system occurred after recovery, and recovery personnel cut the cables. It revealed zero threads exposed on the trim drum jackscrew. The trim cable turnbuckles in the empennage exhibited similar bending characteristics. When investigators repositioned the rear trim cables to align the turnbuckles and the bending damage, the drum exhibited five threads. When they positioned the cables so that the cut ends aligned, trim drum exhibited eight exposed threads. WEIGHT and BALANCE The Mono County Sheriff's Department weighed the baggage, which totaled 257 pounds. The pilot weighed 176 pounds, the right front seat passenger weighed 130 pounds, and the right rear seat passenger weighed 215 pounds. The Piper representative determined that the airplane was within weight and balance limitations. ADDITIONAL INFORMATION The IIC released the wreckage to the owner's representative

Probable Cause and Findings

the pilot's failure to maintain an adequate airspeed resulting in a stall/spin.

 

Source: NTSB Aviation Accident Database

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