NTSB Factual Report

HISTORY OF FLIGHT

On January 17, 2017, at 1055 Pacific standard time, an experimental amateur-built Harmon Rocket, N275JS, impacted terrain following a total loss of engine power during the initial climb from Corona Municipal Airport (AJO), Corona, California. The private pilot (seated in the front seat) was fatally injured, and the commercial pilot (seated in the rear seat) sustained serious injuries; the airplane sustained substantial damage. The airplane was owned and operated by the front-seat pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which originated from AJO at 1026.

According to a Federal Aviation Administration (FAA) inspector, witnesses reported seeing the airplane initially take off from runway 25. The airplane then landed on runway 07 and immediately departed. After reaching 100-200 ft above ground level (agl), the engine experienced a loss of power. The airplane made a steep turn back toward the airport and collided with terrain, coming to rest on flat, soft vegetation on airport property. The accident site was located about 1,650 ft from the departure end of runway 07.

The airplane was equipped with an Advanced Flight Systems AF-4500sEF multifunction display (MFD) that recorded the flight and engine parameters in 5-second increments. The MFD revealed that the airplane departed at 1026 and circled over Lake Mathews, located about 9 miles to the southeast. Thereafter, the airplane returned to AJO and performed three practice takeoffs and landings on runway 25. The airplane then made a 360o turn to the west of the airport and performed a touch-and-go practice takeoff and landing on runway 07.

The airplane became airborne again at 1052:29 and climbed about 270 ft, to 770 ft mean sea level, at which point the fuel flow dropped from about 20 psi to less than 1 psi. The engine's rpm and exhaust gas temperature values drastically decreased, consistent with the engine experiencing a total loss of power. The airplane began a right turn about 1052:34 and collided with terrain at 1052:49. Figure 1 depicts the takeoff from runway 07 and the remainder of the flight.

Figure 1: Takeoff Prior to Accident

PILOT INFORMATION

Front-Seat Pilot

According to the FAA Airman and Medical records, the front-seat pilot, who was the owner and builder of the airplane, held a private pilot certificate with ratings for airplane single- and multi-engine land as well as rotorcraft. He also held a repairman experimental aircraft builder certificate. The pilot was issued an FAA third-class medical certificate in October 2015, with a limitation that he must wear glasses for near vision.

The pilot's most recent personal flight records were not recovered. On his most recent application for a medical certificate, the pilot reported 2,000 total hours of flight experience.

Aft-Seat Pilot

The commercial pilot, positioned in the aft seat, held ratings for airplane single- and multi-engine land; single-engine sea; rotorcraft-helicopter; and instrument airplane. Additionally, he held a flight instructor certificate with ratings for airplane single- and multi-engine. His most recent FAA third-class medical certificate was issued in January 2017 with a limitation that he must have glasses available for near vision.

The pilot's personal flight records were not recovered. On his last application for a medical certificate, the pilot reported 20,000 total hours of flight experience, of which 200 hours was accumulated in the previous 6 months.

It could not be determined who was acting as pilot-in-command at the time of the accident. A witness who knew the owner of the airplane stated that the owner didn't like to fly the airplane without another pilot on board.

AIRCRAFT INFORMATION

The Harmon Rocket was a low-wing, single-engine, experimental airplane, constructed by the owner and completed in 2010 with serial number 0471. The last condition inspection was recorded as being preformed by the owner in October 2016 in accordance with 14 CFR Part 43, appendix D. The entry noted a total time in service of 90.71 hours.

The airplane was equipped with a Lycoming IO-540-C4B5 engine, serial number L-5545-48, modified for experimental use only. The last annual inspection logbook entry in October 2016, noted a total engine time of 90.71 hours. The engine was overhauled by Aircraft Engine Specialists, Chandler, Arizona, in May 2009 and shipped to the pilot shortly thereafter for installation on the airplane.

Fuel System

The airplane's fuel system was a gravity-fed design in which fuel flowed from the metal tanks in the inboard section of each wing, through a selector valve, and continued to an electric fuel pump. From the pump, the fuel was routed to a transducer where it was plumbed through the firewall to the gascolator, which contained a fuel screen. Thereafter, the fuel was directed to the engine-driven fuel pump, and then routed under the left cylinders to the fuel servo (located at the forward bottom of the engine). From the servo, the fuel was routed between the Nos. 1 and 3 cylinders to the fuel distribution manifold (i.e., spider) and then to each cylinder's injector.

Fuel Servo

The fuel servo was a Bendix RSA-5AD1 (part number 2524213-1, serial number 6507-T), manufactured in 1977. The major components of the servo include the airflow section, the flow metering section, and the fuel regulator section. Together, these sections are designed to meter fuel in direct ratio to the volume of air being consumed by the engine (see Figure 2).

The regulator assembly contains an air diaphragm, a fuel diaphragm, and regulator stem that has a regulator ball affixed at the end. The air diaphragm senses impact air and compares it to venturi suction. The fuel diaphragm compares metered and unmetered fuel pressure. The diaphragms are connected by the regulator stem, which passes through the center body section of the regulator. The four chambers in the regulator section of the servo act in unison to cause the diaphragms to equalize and regulate the appropriate amount of fuel to the engine when the airflow is altered. When the engine is operating at a constant throttle setting, opposing forces of the fuel and air diaphragms cause the regulator valve stem to unseat to a specific position and an appropriate quantity of fuel is provided to the engine. As the throttle setting is increased, velocity of air through the venturi increases and pressure decreases within the suction side of the air chamber relative to the impact side. This creates a pressure differential across the air diaphragm and causes the regulator valve (ball at the end of the regulator stem) to move toward a more open position. As the regulator valve opens (ball moves off the seat), more fuel is provided to the engine. Once the pressure differential across the fuel diaphragm stabilizes and reaches a force in equilibrium with the air diaphragm, fuel flow is again stabilized.

Figure 2: Drawing of the Fuel Servo (showing regulator valve)

Maintenance

Several pictures of the accident servo were provided to a representative from Precision Airmotive, which purchased Bendix in 1988. He stated that the internal parts appeared to be original to the servo. He stated that all of the parts inside the regulator side are required replacement items at the time of overhaul. At the time of the servo's manufacture, the overhaul requirements were the same as the time between overhaul specified by the engine manufacturer. In 1991, Precision issued a calendar requirement, wherein the servo must be overhauled every 12 years. After overhaul, the servo should have a yellow data plate attached; the accident servo still had the original black data plate.

A review of maintenance records and invoices showed that the maintenance entry for the engine overhaul was dated May 2009 and noted that the airplane was equipped with a "serviceable fuel servo RSA-5AD1, pn 252-4213-1, sn 6507-T." A representative from the maintenance facility that performed the overhaul stated that "serviceability appears to have been determined by a functional check during the test run of the complete engine." There were no other maintenance records found regarding the servo. Because the airframe and engine were classified as amateur-built experimental, the overhaul criteria are not required for airworthiness.

MEDICAL AND PATHOLOGICAL INFORMATION

The front-seat pilot survived the impact but died in the hospital later that day. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing of specimens from the pilot. The testing revealed 0.006 (ug/ml, ug/g) tetrahydrocannabinol carboxylic acid (THC-COOH), an inactive metabolite of the primary psychoactive drug in marijuana tetrahydrocannabinol, detected in blood. Additionally, the report documented Midazolam, a potent anesthetic used during emergency treatment, consistent with postaccident medical intervention. The presence of trace amounts of THC-COOH in femoral blood is consistent with past use of marijuana, but blood testing did not identify the impairing drug marijuana.

TESTS AND RESEARCH

The front seat had a control quadrant on the left side; the levers were all bent and folded over to the right. The throttle was positioned in a mid-range position and the fuel mixture and propeller controls were full forward.

Both wings remained attached to the airframe; the left fuel tank was breached. Fuel was recovered from both wing tanks. The fuel selector valve was found in the "OFF" position, but witnesses reported that first responders had repositioned the selector. The fuel selector was removed and, when operated, turned smoothly and displayed proper valve function. The fuel pump was removed and investigators connected it to a power source. The pump clicked and air egressed from the outlet. The transducer was removed and disassembled; the wheel was intact and no anomalies were found. The gascolator contained trace amounts of fuel and was free of debris. The upper housing of the fuel manifold was removed; there was no evidence of fuel and the diaphragm was dry.

The engine was mounted on a test stand and fuel was plumbed to the fuel pump; the fuel flowed freely and there was no evidence of blockage. Fuel was then plumbed to the fuel servo and investigators were unable to obtain flow to the outlet. The fuel servo was then removed and replaced with a similar model and fuel ran freely.

The fuel source was then attached to the mechanical fuel pump inlet and the system was reconnected with the exemplar servo. The propeller, damaged from the accident, was removed from the engine and a club propeller was installed. The engine was successfully started and ran for over 5 minutes at various power settings from idle to about 2,700 rpm. A magneto check was conducted on the left and right magnetos with a minimal rpm drop per magneto; no anomalies were found during the engine run.

Fuel Servo

The fuel servo was completely disassembled. The safety wire on the regulator housing had a crimp with a stamp that read "AKB." Upon disassembly of the regulator, investigators noted that the valve stem was separated from the regulator valve (ball) as shown in Figure 3. The accident servo was reassembled and investigators affixed the exemplar servo's regulator section. A fuel source was connected and fuel flowed normally through the servo. The accident regulator section was installed on the exemplar servo and tested; the fuel would not flow. The complete examination notes with pictures are contained in the public docket for this accident.

Figure 3: Fuel Servo's Valve Stem Separated from the Regulator Ball

NTSB Probable Cause

A total loss of engine power during takeoff due to fuel starvation as a result of a failure of internal components of the fuel servo.