CEN14FA462

The misfueling of the airplane with jet fuel instead of the required aviation fuel, and the resultant detonation and a total loss of engine power during initial climb. Contributing to the accident were the line service technician's inadvertent misfueling of the airplane, the pilot's inadequate supervision of the fuel servicing, and the fixed-base operator's use of a small fuel nozzle on its jet fuel truck.

According to the line service technician who worked for the fixed-base operator (FBO), before taking off for the air ambulance flight with two medical crewmembers and one patient onboard, the pilot verbally asked him to add 40 gallons of fuel to the airplane, but the pilot did not specify the type of fuel. The line service technician drove a fuel truck to the front of the airplane and added 20 gallons of fuel to each of the multiengine airplane's wing tanks. The pilot was present during the refueling and helped the line service technician replace both fuel caps. Shortly after takeoff, a medical crewmember called the company medical dispatcher and reported that they were returning to the airport because smoke was coming from the right engine. Two witnesses reported seeing smoke from the airplane Several other witnesses reported seeing or hearing the impact and then immediately seeing smoke or flames. On-scene evidence showed the airplane was generally eastbound and upright when it impacted terrain. A postimpact fire immediately ensued and consumed most of the airplane. Investigators who arrived at the scene the day following the accident reported clearly detecting the smell of jet fuel. The airplane, which was equipped with two reciprocating engines, should have been serviced with aviation gasoline, and this was noted on labels near the fuel filler ports, which stated "AVGAS ONLY." However, a postaccident review of refueling records, statements from the line service technician, and the on-scene smell of jet fuel are consistent with the airplane having been misfueled with Jet A fuel instead of the required 100LL aviation gasoline, which can result in detonation in the engine and the subsequent loss of engine power. Postaccident examination of the engines revealed internal damage and evidence of detonation. It was the joint responsibility of the line technician and pilot to ensure that the airplane was filled with aviation fuel instead of jet fuel and their failure to do so led to the detonation in the engine and the subsequent loss of power during initial climb. In accordance with voluntary industry standards, the FBO's jet fuel truck should have been equipped with an oversized fuel nozzle; instead, it was equipped with a smaller diameter nozzle, which allowed the nozzle to be inserted into the smaller fuel filler ports on airplanes that used aviation gasoline. The FBO's use of a small nozzle allowed it to be inserted in the accident airplane's filler port and for jet fuel to be inadvertently added to the airplane.

Left Engine Examination Examination of the left engine revealed that it exhibited significant fire and impact damage. The oil cooler, induction system, and intercooler were partially melted by the postcrash fire. All of the engine accessories were impact and thermally damaged. The right magneto case was melted, exposing the internal components. Both magnetos cases were melted, and only the rotating magnet remained attached to the engine. The fuel pump was thermally damaged and remained attached to the engine, and the drive coupling was intact. The alternator and propeller governor were thermally damage and remained attached to the engine. The remainder of the external surfaces of the engine exhibited varying degrees of impact and thermal damage. All of the internal components of the left engine exhibited thermal damage but no signs of lubrication distress. The cylinders exhibited heat damage and evidence of detonation. All pistons exhibited scuffing and heat signatures on the skirt. The Nos. 2, 5, and 6 pistons showed evidence of detonation on the face of the piston with portions melted away on the outer edge. The main and rod bearings exhibited normal operating signatures and thermal damage from the postcrash fire. The crankshaft, camshaft, gears, connecting rods, and reduction gears all exhibited thermal damage and normal operating signatures. The crankcase exhibited normal operating signatures and impact and thermal damage. The fuel system components were impact and fire damaged. The engine accessories were intact and exhibited thermal damage. Right Engine Examination Examination of the right engine revealed that it exhibited significant fire and impact damage. The induction system and intercooler were separated. All of the engine accessories were impact and thermally damaged. The right magneto case was melted, exposing the internal components. The left magneto remained attached but exhibited thermal damage. The fuel pump was thermally damaged and remained attached to the engine. The drive coupling was intact. The alternator and propeller governor were thermally damaged and remained attached to the engine. The remainder of the external surfaces of the engine exhibited varying degrees of impact and thermal damage. All the internal components of the right engine exhibited thermal damage due to the postcrash fire but no signs of lubrication distress. The cylinders exhibited heat damage and evidence of detonation. All pistons exhibited scuffing and heat signatures on the skirt. The Nos. 1, 2, and 5 pistons showed evidence of detonation on the face of the piston with portions melted away on the outer edge. The main and rod bearings exhibited normal operating signatures and thermal damage from the postcrash fire. The crankshaft, camshaft, gears, connecting rods, and reduction gears all exhibited normal operating signatures. The crankcase exhibited normal operating signatures and impact and thermal damage. The fuel system components were impact and fire damaged with portions melted away. The engine accessories were intact and exhibited thermal damage. Only portions of the induction system remained attached to the right engine; the remainder was melted away by the postcrash fire. Federal Guidance According to the FAA Pilot Handbook of Aeronautical Knowledge, page 6-19: Detonation is an uncontrolled, explosive ignition of the fuel/air mixture within the cylinder's combustion chamber. It causes excessive temperatures and pressures which, if not corrected, can quickly lead to failure of the piston, cylinder, or valves. In less severe cases, detonation causes engine overheating, roughness, or loss of power." According to the FAA Airframe & Powerplant Mechanics Powerplant Handbook, AC 65-12A, Chapter 10, Unless detonation is heavy, there is no cockpit evidence of its presence. Light to medium detonation may not cause noticeable roughness, observable cylinder head or oil temperature increase, or loss of power. However, when an engine has experienced detonation, we see evidence of it at teardown as indicated by dished piston heads, collapsed valve heads, broken ring lands or eroded portions of valves, pistons and cylinder heads. Severe detonation can cause a rough-running engine and high cylinder head temperature." According to FAA Advisory Circular (AC) 20-122A, "Anti-Misfueling Devices: Their Availability and Use," paragraph 6.1 , "Aviation statistics indicate that the use of improper fuel has caused or contributed to an inordinate number of accidents and incidents. Most of these have involved single-engine aircraft (and some multiengine) that were misfueled with jet or turbine engine fuel instead of gasoline, which these aircraft use. Misfueling a reciprocating engine-powered aircraft with jet…fuel can and has produced catastrophic results when engines failed during the critical takeoff phase of flight." Paragraph 6.3, states, "Fuel tank filler openings in reciprocating engine-powered aircraft may be equipped with pilot-installed adapter rings reducing the opening size from 3 inches to 2.3 inches in diameter. Jet or turbine engine fuel nozzle assemblies will be equipped with spouts with a minimum diameter of 2.6, thereby reducing the probability of introducing jet or turbine engine fuel nozzles into the filler openings of aircraft requiring gasoline." Paragraph 7.3, states, in part, "in the interest of safety and standardization, it is recommended that Fixed Base Operators…equip their turbine fueling equipment…with the larger size nozzles…to prevent misfuelling." According to FAA AC 150/5230-4B "Aircraft Fuel Storage, Handling, Training, and Dispensing on Airports," page 1, Paragraph 3, "Application," "This AC provides an acceptable means of complying with Title 14 Code of Federal Regulations (CFR) part 139 (hereinafter referred to as Part 139) for all Part 139 airport operators. Although non-certificated airports are not required to develop fuel standards, the FAA recommends these airports use the guidance contained in this AC to develop such standards for the continued enhancement of aviation safety." Page 7, chapter 2, paragraph 1, e, states, "14 CFR §139.321 (b) places the responsibility of determining standards for fueling safety on the individual airport based on state, local, or municipality fueling regulations. The FAA does not intend this AC to replace airport procedures that are tailored to meet requirements imposed because of the use of special equipment or as a result of local regulations." Industry Guidance In 2005 , the Aircraft Owners and Pilots Association Air Safety Foundation issued Safety Brief Number 4 SB04-07/05, "Misfueling." The safety brief cautioned about the dangers of misfueling and recommended that pilots specify the fuel type and grade when ordering fuel, be present at the refueling and actively observe the fueling process, match the fuel truck color coding with the wing fueling decal, confirm that the fuel nozzle is compatible with the aircraft's fuel filler, and confirm that the fuel grade on the invoice matches the fuel grade ordered. The July/August 2006 issue of National Air Transportation Association's "NATA Safety 1st eToolkit," Page 1, "Aircraft Misfueling – A Continuing Threat," recommended that an effective misfueling prevention program should be adopted into the standard practices at all fueling operations and that the prevention program should include the following: "Training; Grade Confirmation; Written Fuel Order Forms; Grade Decals for Aircraft and Fueling Equipment; Selective Nozzle Spouts; and Fuel Receipt Quality Control Procedures." In March 2016, the NTSB issued a Safety Alert SA-050 "Pilots: Fueling Mistakes." The General Aviation Safety Alert cautioned pilots on the dangers of misfueling and gave several recommended preventive safety procedures. In March 2016, the NTSB issued a Safety Alert SA-051 "Line Personnel: Fueling Matters".