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On May 28, 2009, about 0845 mountain daylight time, a Maule M-5-210C, N315X, impacted uneven terrain after experiencing a loss of engine power during takeoff at Ogden-Hinckley Airport, Ogden, Utah. The pilot was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certificated airline transport pilot sustained serious injuries. The airplane sustained substantial damage to the forward fuselage and both wings. The local flight departed Ogden about 0845, with a destination of Paradise, California. Visual meteorological conditions prevailed, and no flight plan had been filed.
The pilot reported that the intention of the flight was to reposition the airplane to Anchorage, Alaska. Due to the nature of his injuries, he was unable to submit a written report until a month following the accident. He stated that on the day prior to the accident he performed what he described as an in-depth walk around of the airplane. During the inspection he verified that there was about 10 gallons of fuel in each main fuel tank. He subsequently taxied the airplane to the run-up area and performed an uneventful, "in-depth engine run-up check procedure."
The pilot reported that the following morning he checked the weather, and then filled both the main and auxiliary fuel tanks with the addition of 43 gallons of 100 low lead aviation gasoline. The pilot then taxied the airplane to runway 34, and completed an uneventful before takeoff check and engine run-up.
The pilot reported that during the takeoff roll the engine parameters appeared normal, the airplane rotated, and then continued to accelerate throughout the climb. The airplane continued to climb to about 700 feet above ground level (agl) when the pilot initiated a climbing left turn to the west. About 1,100 foot agl he reduced the propeller speed and manifold pressure to 2,450 rpm and 24 inches, respectively. Shortly thereafter the engine stopped producing power. The propeller continued to rotate, and the pilot rolled the airplane into a 45-degree left bank. He lowered the nose and trimmed the airplane for 80 knots airspeed. He then applied full forward throttle and propeller control, confirmed the mixture was still at a full rich setting, and turned on the auxiliary fuel pump. During the descent he continued with troubleshooting procedures; however, the engine did not restart and he performed a forced landing in a grass field northeast of the airport. He reported that during the descent he experienced difficulties maintaining the correct airspeed and descent rate. Just prior to impact he pulled the throttle, propeller, and fuel mixture controls to the full aft position.
The pilot reported that prior to the accident he asked the owner of the airplane if he had ever used automotive gasoline in the airplane, to which he replied that he had not.
The NTSB investigator-in-charge interviewed the airplane owner after the accident. The owner stated that he had used automotive gasoline in the airplane in the past, but "had given up that practice" and had been using aviation gasoline since January 2009. He additionally stated that he had brought his use of automobile gasoline to the attention of the pilot.
The pilot, age 49, held an airline transport pilot certificate with ratings for airplane single-engine land and multiengine land. The pilot held a certified flight instructor (CFI) certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. He reported 5,900 hours total time in all aircraft, with 150 hours in the accident make and model. He reported his principal occupation to be that of a pilot.
A review of Federal Aviation Administration (FAA) airman records revealed that the pilot held a first-class medical certificate issued in February 2009, with the limitation that he must have glasses available for near vision.
The single-engine, high-wing, airplane was manufactured in 1975 and was equipped with a Teledyne Continental Motors (TCM) IO-360-D fuel injected engine, and a McCauley constant speed propeller.
A review of the airplane’s maintenance logbooks and tachometer at the accident site revealed that it had accumulated a total flight time since manufacture of 1,613 hours. Additionally, an annual inspection was completed on December 4, 2008, 48.5 flight hours prior to the accident. At that time, the engine had accumulated a total of 1,565.5 flight hours since its manufacture in 1975. According to the logbook, the airplane had not been subject to a major overhaul since its manufacture.
The logbooks indicated that on March 22, 2009, two flight hours prior to the accident, the number 5 and number 2 engine pushrod seals were replaced. The final logbook entry dated April 27, 2009, reported the addition of a four point inertia reel safety belt system, and a Maule super skylight kit. The entry stated the "estimated" tachometer time for this entry to be 1,614.0 hours.
The airplane was equipped with four wing fuel tanks and a header tank; according to the airplane flight manual, the total fuel capacity was 63 gallons.
The closest aviation weather observation station was located at Ogden-Hinckley Airport. An aviation routine weather report (METAR) for Ogden was issued at 0853 MDT. It reported: winds calm; skies clear; temperature 19 degrees C; dew point 4 degrees C; altimeter 30.13 inches of mercury.
WRECKAGE AND IMPACT INFORMATION
A Federal Aviation Administration inspector (FAA) responded to the accident site. He examined the gascolator and observed that it was clear of debris, and contained clear blue fluid consistent in color and odor with aviation gasoline.
The airplane sustained crush damage from the engine firewall through to the cabin, aft of the wing trailing edges. The left wing separated at its aft spar attach point, was facing forward, and partially attached to the forward spar. The right wing remained partially attached at the forward and aft spar and had become folded down at its intersection with the wing struts. The propeller separated from the crankshaft at the flange, and came to rest about 10 feet forward of the airplane.
TESTS AND RESEARCH
The engine remained attached to the firewall. The throttle and propeller control cables were continuous from the cabin controls through to their respective engine controls. The fuel mixture cable was continuous from the cabin control through to the engine side of the firewall, where it had become separated from the fuel servo at the mixture arm. The fracture surfaces of the mixture arm and elevator control rod were granular in appearance, with the mixture arm exhibiting a 45-degree sheer lip.
The left magneto had become separated from the engine at its mounting flange, and exhibited external damage. The right magneto remained attached to its mounting pad. The ignition cables for both magnetos appeared undamaged. Both magnetos were removed from the engine and tested using a magneto test stand. During the test, sparks were noted at the ignition leads of each magneto.
The top spark plugs were removed and visually examined. The electrodes showed normal erosion patterns when compared to the champion AV-27 chart. The electrodes were dark in color with sooty deposits, which indicated carbon fouling when compared with the champion chart. The spark plugs were of type Unison Autolite, part number URHM-38E, which the Teledyne Continental Motors (TCM) representative stated were appropriate for the engine.
The FAA inspector tested the magneto switch and did not observe any short-circuits.
The fuel manifold valve was disassembled; fuel was noted within its cavity, and its screen was clear of debris. Traces of fuel were observed throughout the engine driven fuel pump, throttle body, and associated supply lines.
Inspection of the engine cylinders with a lighted borescope revealed the combustion chambers of cylinders number 1, 3, and 5 to be coated with sooty deposits. Cylinders number 2, 4, and 6 were coated in a dark oily residue. The crankshaft was rotated by hand from the propeller governor drive shaft. Rotation confirmed drive train continuity, and thumb compression was obtained on all cylinders.
A full examination report of the engine is included within the public docket of this accident.
The rudder control cables were continuous from the rudder horns through to their respective foot pedals. The elevator control cables were attached at the control surfaces, and continuous through to the cabin area. Damage to the fuselage and wings precluded confirmation of control continuity, and rigging for the remaining airplane controls.
The wing fuel tank ventilation lines were clear and free of obstructions.
Application of electrical current to the fuel pump supply leads revealed that it operated intermittently. Disassembly of the fuel pump revealed that the pump section could be rotated freely by hand, and no obstructions were noted to the fuel passages. The drive motor shaft had become seized within the housing, and could not be rotated. Damage to the cabin area prevented confirmation of the auxiliary fuel pump switch position.
Fuel Sample Testing
Fuel was recovered from a wing fuel tank at accident site by the FAA. Damage to the forward fuselage and fuel lines precluded a sample being taken from the header tank. The sample was sent to Utility Testing Laboratory for testing. A fuel fingerprint test was performed; analysis of the test results revealed that the fuel appeared to be predominantly aviation gasoline, mixed with a residual quantity of automotive gasoline.
The Maule airplane flight manual (AFM), and TCM operators manual applicable to the airplane and engine, both require the airplane to be fueled with a minimum 100-130 grade aviation gasoline. Additionally, TCM Service Bulletin M77-3 applicable to the accident engine states in part:
"TCM does not recommend or authorize the use of automotive fuels in any of their aircraft engines….Automotive fuels can contain additives that act as corrosive agents, formulate gum deposits and, therefore, increase combustion chamber deposits. Continued operation on automotive fuel can lead to detonation, pre-ignition and sticking or eroded valves.
The vapor pressure of automotive fuels exceeds that allowable for aviation fuels. This increased vapor pressure increases the tendency to vapor lock at higher altitudes. A vapor lock condition can cause complete power loss."
The TCM representative stated that there are no Supplemental Type Certificates for this airplane providing for the use of automobile gasoline.
According to TCM Service Information Letter (SIL) 98-9A - Time Between Overhaul Periods - the IO-360-D engine is to be overhauled every 1,500 hours of operation or 12 years, whichever occurs first.
The TCM engine operators manual states that the auxiliary fuel pump is used for both starting and as an emergency pump to supply fuel in flight if the engine driven pump fails.
The Maule AFM did not provide guidance regarding fuel mixture settings during takeoff, however it stated that during an emergency engine air restart, at elevations above 8,000 feet, 'a leaner mixture may be required'
According to FAA publication Advisory Circular (AC) AC 65-12A, fuel normally remains in a liquid state until it is discharged into the air stream and changes into a vapor. Under certain conditions the fuel may vaporize in the lines, pumps, or other fuel components. The vapor pockets formed by the premature vaporization can restrict the fuel flow through units that were designed to handle liquids rather than gases. The resulting partial or complete interruption of the fuel flow is called vapor lock.