N145MM

On December 13, 2018, about 1400 eastern standard time, a Czech Sport Aircraft PiperSport, N145MM, was substantially damaged when it was involved in an accident near Punta Gorda, Florida. The sport pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to the pilot, the accident occurred on the second flight of the day. He departed Punta Gorda Airport (PGD), Punta Gorda, Florida, about 1015 with 29 gallons of 100 low lead aviation fuel on board and flew about 40 minutes to Winter Haven’s Gilbert Airport (GIF), Winter Haven, Florida, uneventfully. He departed GIF about 1330 for the return flight to PGD. About 4 miles from PGD, at an altitude of 1,000 ft, the pilot was cleared to land on runway 15.

According to the pilot, while on an extended base leg of the traffic pattern, he turned on the electric auxiliary fuel pump as prescribed in the descent checklist. As soon as he activated the switch, the engine lost all power. He switched fuel tanks and attempted to restart the engine but was unsuccessful. Unable to reach the airport and at an altitude too low to deploy the airframe parachute, he selected a small field for a forced landing and advised the PGD control tower of his intention to conduct an emergency landing. During landing, the airplane struck a fence and a utility pole.

According to data logs downloaded from the airplane’s Dynon EMS-D120 engine data monitor and EFIS-D100 electronic flight information system, the engine’s fuel flow increased to its highest value of about 7 gallons per hour (GPH) during takeoff. After climbout, the cylinder head temperature remained below about 200°F for the duration of the flight. During cruise, the fuel flow was consistently between 5.5 and 6 GPH, and the fuel pressure values remained relatively constant (near 3.9 pounds per square inch [psi]) during the first portion of the cruise phase of flight. About halfway through the cruise phase, the fuel pressure decreased to about 2.9 psi, and then fluctuated between about 2.5 psi and 3.9 psi.

Near the end of the flight, the engine power decreased from about 4,700 rpm to 1,300 rpm over 52 seconds. Immediately afterward, engine power decreased to 0 rpm over 7 seconds, where it remained until impact about 40 seconds later (at the time the engine lost power, the recorded values for fuel quantity were 8.3 gallons in the left tank and 13.1 gallons in the right tank). Just as the rpm began to decrease from 1,300, the fuel pressure decreased from about 3.3 psi to 1.1 psi. As the fuel pressure decreased, the fuel flow increased momentarily from 1.9 GPH to 2.8 GPH before decreasing to 0 GPH. After impact, the fuel pressure increased to about 2.75 psi, where it remained until the recorded data ended, about 10 seconds later (see figure).

Figure - Selected data from engine monitor at end of flight.

The airplane was equipped with an engine-driven mechanical fuel pump and an electric auxiliary fuel pump. In August 2018, the manufacturer issued Safety Directive SA-SC-011, which amended the pilot’s operating handbook to indicate “The electrical fuel pump shall be ON during engine start, engine warm up, taxiing, take-off, climb, approach and landing.” Prior to this directive, the pilot’s operating handbook prescribed use of the electric auxiliary fuel pump only during engine start.

A review of the engine data from the previous flight revealed that the fuel pressure values remained relatively constant (about 3.9 psi) for the duration of the cruise phase. During climbout on the second previous flight, the fuel pressure decreased from about 3.5 psi to 2.5 psi over about 30 seconds. During the cruise phase, the fuel pressure increased to about 3.5 psi and remained relatively constant for the remainder of the cruise phase.

On-site examination of the wreckage by a Federal Aviation Administration inspector revealed that all major components of the airplane were present at the accident site. The right wing was substantially damaged outboard of the wing root, and a section outboard of the flap was completely separated. The left wing was substantially damaged aft of the spar and forward of the flap at the wing root, and along the entire chord outboard of the aileron. An unquantified amount of fuel was present in both the left and right fuel tanks.

Postaccident examination of the engine revealed that there were no obstructions to the air intake or the exhaust. All ignition leads were secure and intact. The top spark plugs were removed and appeared “worn normal.” Thumb compression was observed on all cylinders. A borescope examination of each cylinder revealed no damage to the piston tops, cylinder walls or valves.

An external fuel source was plumbed to supply fuel to the engine. The engine was started, a run-up was performed, and the engine operated normally up to full power. The electric auxiliary fuel pump was cycled on and off several times during the engine run. No anomalies were noted. The engine was shut down, restarted, and run two more times.

According to the engine’s operating manual, the upper operating limit of the cylinder head temperature was 275°F, the minimum fuel pressure was 2.2 psi, and the minimum idle speed was 1,400 rpm. A review of the recorded data revealed that, during the accident flight, the oil temperature, cylinder head temperature, and exhaust gas temperature were all within the operating limits specified by the manufacturer.