History of Flight
On May 2, 2017, at 1528 Pacific daylight time, a Piper PA-32-260 airplane, N3457W, struck power transmission cables and traffic lights and collided with the ground in Mukilteo, Washington, after a partial loss of engine power during the initial climb from Snohomish County Airport (Paine Field), Everett, Washington. The private pilot was not injured; the passenger received minor injuries. The airplane sustained substantial damage. The airplane was registered to Klamath Aviation LLC. and operated by the pilot as a personal cross-country flight under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight was originating at the time and destined for Crater Lake-Klamath Regional Airport, Klamath Falls, Oregon.
The pilot stated that he had just serviced the airplane with aviation gasoline prior to takeoff and filled the main tanks to the "tabs," and both tip tanks to capacity. He performed a preflight walk-around and checked the fuel for contamination at the sump drains. No anomalies were noted. Due to a Boeing 787 performing tests at the arrival end of runway 16R, the pilot accepted an intersection departure from runway 16R at taxiway A4, with about 5,600 ft of runway remaining. He taxied to the runup area adjacent to the intersection and performed pre-takeoff checks and an engine runup; all systems were normal, including magneto and carburetor heat checks. After turning on the auxiliary fuel pump and confirming the fuel selector valve was set to the right tip tank, he taxied onto the runway and began the departure roll. Surveillance video showed the airplane was in the runup area for about 3 minutes and began the takeoff roll about 30 seconds later.
The airplane accelerated appropriately, and the pilot initiated a rotation at 80 mph. The airplane lifted off and continued to accelerate to 90 mph during the initial climb. The air traffic controller requested a right turn when able due to departing traffic behind; as the pilot began to initiate the turn, the engine lost power. The pilot estimated the power loss occurred at about 400 ft agl, and the airplane could not maintain altitude. He declared an emergency, checked the fuel selector valve and fuel mixture positions, and confirmed the engine primer was in and locked. With limited time, he turned his attention to a forced landing. During the descent, the engine appeared to be producing partial power, and the propeller continued to turn at 400 to 500 rpm.
The pilot observed an area of swamps and tall trees directly ahead, and to the right a busy six-lane road running north-south. He could see to the right an east-west oriented road free of traffic in the westbound lane. He maneuvered for landing in that lane; as he approached, the right wing struck a power transmission cable. Both wingtips then struck separate traffic lights, rupturing the tip tanks and spraying ignited fuel over cars waiting at the intersection below. The airplane then collided with the ground and came to rest on the street.
A witness positioned in his automobile at an intersection adjoining the runway reported that his attention was drawn to the airplane during takeoff because it was emitting bursts of visible "exhaust." He stated he was familiar with aircraft traffic and was drawn to look because the exhaust trail was not normal.
Aircraft Information
The airplane was manufactured in 1966 and purchased by the pilot and passenger, who were the sole members of Klamath Aviation LLC., on November 15, 2016. The most recent maintenance event was an annual inspection completed on September 21, 2016, at a total airframe time of 5,766.32 flight hours. At inspection, the engine had accrued 567.42 flight hours since overhaul in September 1997.
Meteorological Information
A special aviation routine weather report for Paine Field at 1549 included wind from 210° at 3 knots, temperature 15°C, dew point 9°C. The carburetor icing probability chart from FAA Special Airworthiness Information Bulletin CE-09-35 indicates a probability of serious icing at cruise power for the reported temperature and dew point.
Wreckage and Impact Information
The airplane came to rest on a west heading on the street about 2,200 ft beyond the end of runway 16R and 10° right of the runway centerline. The main cabin and left wing were largely intact. The horizontal stabilizer had detached, leaving the vertical stabilizer partially attached to the tailcone. The right wing had folded up about 45° at the root, and its main fuel tank had been breached. An FAA inspector checked the left main fuel tank, the only unbreached tank, and found it contained fuel. He then removed the carburetor bowl drain plug, and fuel drained from the bowl.
The airplane was recovered and examined by the NTSB investigator-in-charge, FAA inspectors, and technical representatives from Lycoming Engines and Piper Aircraft.
Examination Findings
All fuel lines and fittings were intact from the fuel tanks through to the carburetor, with no indications of a fuel leak. The fuel selector bowl contained about 1/4 cup of clean, bright, light-blue colored fuel. The fuel selector valve moved freely with positive detents. The fuel was tested with water-detecting paste; no water was found. The engine sustained minimal damage and remained partially attached to the firewall, with the upper left engine mount broken. The propeller was still attached to the crankshaft; both blades exhibited about 360° of tip curl with chordwise scratches. One blade tip had detached. The dipstick indicated the engine contained 6 quarts of oil. Top and bottom spark plugs were Champion REM 38E types with normal wear; some plug electrodes were coated in dark grey/black soot, consistent with "carbon fouled."
The engine was readied for a test-run using fuel from the airplane's left wing main tank. After two cranking attempts, the engine started and operated smoothly for about 4 minutes at speeds from 700 to 2,500 rpm. Each magneto indicated a 100 rpm drop when tested at 1,500 rpm. After the run, the top spark plugs were removed; the black soot was gone, replaced with dark grey coloration.
The carburetor and both magnetos were removed and examined. Both magnetos produced sparks in firing order throughout their operating speed range. The carburetor appeared undamaged; all fittings were intact. The fuel inlet screen was clear. The carburetor bowl screws were secure and tight. Internal examination revealed a brass float assembly that was intact but with clearance out of tolerance. Rub marks were present on the inner surface of the bowl walls, indicating float contact. The float was slightly twisted, with one side resting 1/16th inch above the other. Float leak test found none.
Service Bulletin SB-4 Rev. B, published by Volare Carburetors, LLC, on September 2, 2009, documented reports of stuck, leaking, or worn floats when float-to-bowl clearance was incorrect. The bulletin recommended measuring clearance immediately if symptoms existed, or within 100 flight hours or 90 days, and replacing floats if tolerance was not met, then stamping "FC" on the mounting flange. No logbook entry indicated compliance, nor was there evidence of "FC" stamping.
White thread sealant compound was found on multiple fittings and bolt threads throughout the carburetor, including the inlet filter screen. Service Bulletin SB-10 Rev B, published August 12, 2010, by Marvel-Schebler, prohibits the unauthorized use of such sealant, as it may break away and clog internal fuel passages. The bulletin calls for immediate overhaul if any traces are observed.
Service Bulletin MSA-3 revision 1, published by Precision Airmotive on November 18, 1991, describes overhaul periods for MA series float-type carburetors and recommended replacement within 10 years of placement into service.
Additional Information
A fuel receipt from a fixed based operator at Paine Field showed that the airplane was serviced with 41.2 gallons of 100 octane low-lead aviation gasoline about 30 minutes before the accident. The facility manager stated that two other aircraft purchased fuel immediately after and reported no issues; he also checked the fuel storage and delivery system for water contamination and found none.