Skip Ribbon Commands
Skip to main content
Full Narrative

Quick Launch
NTSB Identification: CEN15LA199

On April 17, 2015 at 0745 central daylight time, a Cessna 421B airplane, N421PK, lost engine power made a forced landing onto a highway near Diboll, Texas. The airplane was substantially damaged. The pilot sustained serious injuries and the two passengers sustained minor injuries. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions prevailed at the time of the accident and the flight operated on an instrument flight rules (IFR) flight plan. The flight departed from the Angelina County Airport (LFK), Lufkin, Texas at 0737 and was en route to the West Houston Airport (IWS), Houston, Texas.

According to the pilot, he landed the airplane the day before and requested that the tip tanks be topped off with fuel. The next morning he performed a preflight inspection on the airplane; there was no water in the fuel sample, which appeared blue like 100LL aviation gasoline. After a normal engine run-up, he and the two passengers departed. During the climb out, the airplane had a slight vibration and the climb performance was degraded. The airplane reached 2,100 feet above ground level and the left engine sputtered and lost all power. Within 30 seconds, the right engine also lost all power and he descended for a forced landing. The airplane landed hard and came to rest in the grassy median of a highway. During the accident sequence the wings and fuselage were damaged and the right fuel tank ruptured. The pilot added that the smell of Jet A fuel was prominent at the accident scene.

The fixed based operator (FBO) employee who fueled the airplane stated that the pilot requested that he top off the tip tanks with fuel. The employee mistook the accident airplane for a similar airplane that uses Jet A fuel. He brought the Jet A tuck over and fueled the airplane. He noted that the nozzle on the Jet A fuel truck was small and round like the nozzle on the aviation gas fuel truck. The round nozzles were always on the Jet A fuel truck because of the prevalent military helicopter traffic utilizing the FBO's services. He stated that it was a lot easier to fuel the helicopters with the round nozzle. He did not know who changed the nozzles and recalled that they were always like that. He stated that the pilot paid for the fuel and signed the receipt, which noted Jet A fuel was used.

According to the LFK airport manager, the nozzle was switched to the small round nozzle in order to more easily and efficiently fuel the military helicopters that were serviced at the airport. The usual nozzle for Jet A was a larger J-shaped nozzle with an opening of 2 ¾ inches.

Fuel records obtained from LFK revealed that the accident airplane was fueled with 53 gallons of Jet A on the day prior to the accident. A review of the records revealed a credit card receipt signed by the pilot. The printed receipt showed 53 gallons of Jet A with FGII additive. The FBO's invoice had Jet A and Avgas preprinted on the form; the details of the sale were annotated on the invoice, including a circling around "Jet A".


The pilot, age 63, held a private pilot certificate with ratings for single engine and multi-engine land airplane. He also held an airplane instrument rating. On April 30, 2014, the pilot was issued a third class medical certificate without limitations or waivers. The pilot report that he had accumulated about 3,000 total flight hours, 500 of which were in the accident airplane make and model. In the preceding 90 and 30 days he had flown 39 and 10 hours respectively in the accident airplane make and model.

The FBO employee was a current line serviceman and possessed the required training to fuel aircraft. On January 13, 2015, he passed the AvFuel Quality Assurance Training tests which were administered by the FBO management. The manager had never experienced an aircraft misfueling under his direction in the past.


The 6 seat, low wing, retractable landing gear airplane, serial number 421B0830, was manufactured in 1975. The airplane was powered by two reciprocating GTSIO-520-H Continental Motors engines rated at 375-horsepower, which each drove a 3-blade, full feathering, constant speed McCauley propeller. The airplane was equipped with main outboard fuel tanks (tip tanks) and inboard auxiliary fuel tanks.

A review of the maintenance logbooks revealed that on April 10, 1997, the airplane registration was changed from German registration D-IAEL to United States (US) registration N421PK. An entry in the records noted that the aircraft mechanic found the airplane to meet the requirements for a US standard-normal category airworthiness certificate. Issuance of the airworthiness certificate indicated that all applicable airworthiness directives were completed. The listing also showed Airworthiness Directive (AD) 87-21-02 R1, had been previously complied with.

The last annual inspection was completed on October 17, 2014, at an aircraft total time of 5,212.2 hours. A list of the applicable airworthiness directives were signed off as completed.


At 0753, the automated weather observation at LFK, located 5 miles northeast of the accident site, reported wind calm, 10 miles visibility, overcast cloud layer at 800 feet, temperature 66°F, dew point, 63° F, and altimeter 29.98 inches of mercury.


A postaccident examination of the airplane and engines was conducted on April 24, 2015. The engines exhibited signs of detonation. The cylinders showed no combustion deposits, scrape marks were noted on the cylinder walls and metal particles were noted on the piston face. The sparkplugs showed signs of normal wear when compared to a Champion Check-A-Plug comparison card, but heavy dark deposits were noted in the electrode areas. No water contamination was found in either fuel strainer bowl. The airplane's fuel tank filler ports were not equipped with restrictors a required by AD 87-21-02 R1. Two fuel placards were located near the filler ports, one read: AVGAS ONLY – grade 100LL. The other placard, located just under the filler port read: Fuel, 100/130 aviation grade min, useable 50 gal.


Cessna Service Information Letter

On July 20, 1984, Cessna Aircraft Company issued a Service Information Letter ME84-31: Fuel Filler Diameter Modification and External Turbo Placard Removal. This was effective for the accident airplane and stated in part: fuel filler modification kits are being made available to reduce the size of the filler port on multiengine piston aircraft. The reduced size fuel port is sized to allow normal fueling with aviation gasoline hose nozzles but will prevent entry of the larger jet fuel hose nozzles as an aid in reducing misfueling errors. However, the only positive method of ensuring that correct fuel is used it to carefully follow proper fueling procedures.

Airworthiness Directive

On June 16, 1989, the Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 87-21-02 R1, to preclude misfueling of an airplane which would result in an engine failure. The AD mandated within the next 12 calendar months, for all applicable aircraft, all fuel filler openings should be modified in accordance with ME84-31. The accident airplane was included in the applicable aircraft.