History of Flight
On August 27, 2014, about 1903 mountain daylight time, a Cessna 421C airplane, registration N51RX, impacted terrain during initial climb near Las Cruces International Airport, Las Cruces, New Mexico. The airplane was operated by Amigos Aviation, Inc. as a 14 Code of Federal Regulations Part 135 air ambulance flight. Day visual meteorological conditions prevailed at the accident site, and an instrument flight rules flight plan had been filed. The flight departed Las Cruces destined for Phoenix Sky Harbor International Airport.
Earlier, the airplane arrived at Las Cruces about 1822 to load a patient. According to the line service technician, when both engines were shut down, the pilot asked to add 40 gallons of fuel without specifying type. The technician added 20 gallons to each wing tank. The pilot assisted in replacing the fuel caps and signed the fuel ticket.
At 1901:45, shortly after departure, a medical crewmember called the company dispatcher and reported smoke from the right engine. A witness on the interstate saw the airplane about 200 feet above ground level with smoke from the right engine, then descending and entering a left turn. Another witness saw smoke trailing as the airplane passed about 100 feet above him. Several witnesses reported seeing or hearing the impact and immediately seeing smoke or flames.
Personnel Information
The pilot held an FAA airline transport pilot certificate with single-engine and multiengine land ratings, and a flight instructor certificate. He held a first-class medical certificate issued October 28, 2013. Based on records, his estimated flight experience was 2,432 total hours, including 1,553 hours in multiengine airplanes and about 1,379 hours in Cessna 421 airplanes.
The line service technician had been employed by the fixed-base operator since April 7, 2014. He had no previous aviation work experience, held no FAA airman certificate, and was not a pilot or mechanic. He had completed the FBO's on-job-training program and held an American Petroleum Institute Class C certificate. At the time of refueling, he was the only employee on duty.
Aircraft Information
The airplane was a 1981 low-wing, retractable-landing-gear, pressurized, multiengine Cessna 421C, serial number 421C0871. It was powered by two 375-horsepower Continental Motors GTSIO-520-L turbocharged engines. Each engine drove a three-bladed, variable-pitch, full-feathering McCauley propeller. An annual inspection was completed March 5, 2014, at 8,181.4 aircraft total time. The airplane was equipped with Micro Aerodynamics vortex generators.
Preaccident photographs showed labels near the fuel filler ports reading "AVGAS ONLY." Postaccident review of refueling records and the technician's statements revealed that the airplane had been misfueled with 40 gallons of Jet A fuel instead of the required 100LL aviation gasoline.
The airplane was not equipped with a cockpit voice recorder or flight data recorder, and was not required to be.
Meteorological Information
At 1855, the automated weather observing system at Las Cruces, about 4 miles northeast of the accident location, reported wind from 040° at 5 knots, visibility 10 miles, broken clouds at 6,500 feet, temperature 23°C, dew point 16°C, and altimeter setting 30.16 inches of mercury.
Wreckage and Impact Information
The airplane impacted desert grasslands at a terrain elevation of about 4,420 feet mean sea level. Evidence showed the airplane was eastbound and upright at impact, resulting in separation of the left propeller blades and right aileron. The airplane came to rest inverted about 78 feet east of the initial impact point on a debris path of about 93°. A postimpact fire consumed most of the airplane. Investigators detected the smell of jet fuel at the scene.
Both engines, most of the left wing, the inboard portion of the right wing, and all tail surfaces remained attached. Control cable continuity was confirmed except for separations consistent with cuts or tensile overload. Thermal and impact damage prevented assessment of cockpit instruments. Left aileron trim corresponded to about 21° tab trailing edge down (nose up); right elevator trim also about 21° down; rudder trim neutral; flaps about 9° down; landing gear appeared retracted.
Left propeller blades were separated; none showed significant twisting or gouges but some bending. Right propeller assembly remained attached with some blades melted or bent. Fuel caps were secure; filler ports had 2-inch restrictive inserts.
Medical and Pathological Information
An autopsy of the pilot listed the cause of death as thermal injuries, inhalation of products of combustion, and blunt thoracoabdominal trauma. Forensic toxicology detected 17 mg/hg ethanol in urine and unquantified n-propanol, but no ethanol in blood or liver, consistent with postmortem production.
Tests and Research
Examination of both engines revealed evidence of detonation. The left engine cylinders showed heat damage and detonation; pistons exhibited scuffing and melted edges on Nos. 2, 5, and 6. The right engine similarly showed detonation damage on pistons Nos. 1, 2, and 5. Both engines had normal operating signatures on bearings and internal components aside from thermal damage from the postcrash fire.