Pilot Reported That He Observed A “Significant Drop In Manifold Pressure…”
Location: Nashville, TN Accident Number: ERA21LA070
Date & Time: December 12, 2020, 12:50 Local Registration: N7639P
Aircraft: Piper PA24 Injuries: 1 Minor
Flight Conducted Under: Part 91: General aviation – Personal
On December 12, 2020, about 1250 central standard time, a Piper PA-24-180 airplane, N7639P, was substantially damaged when it was involved in an accident near Nashville, Tennessee. The commercial pilot incurred minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot reported that he departed with 54 gallons of fuel for the cross-country flight and switched tanks every 30 minutes while enroute. After an un-eventful enroute segment of flight, during the approach, about 7 nautical miles from the destination, the pilot reported that he observed a “significant drop in manifold pressure and change in engine noise, best described as a steady roll-back.” He reported that at the time of the loss of engine power, the airplane was still in a “cruise configuration” with the mixture leaned and the landing gear up.
The pilot subsequently pitched for best glide speed, began looking for an open area to land, and started troubleshooting the loss of power. He reported that he switched the fuel selector from the left tank to the right tank, moved the mixture and propeller levers full forward, turned on the boost pump, and engaged the engine starter, however, none of the actions restored power.
The pilot continued his approach to a field that had trees and a house in the flight path. Just prior to impact the pilot reported that he could feel the onset of an aerodynamic stall and the airplane touchdown hard and skidded to a stop in the field.
Examination of the airplane by a Federal Aviation Administration (FAA) Inspector found that the fuselage and both wings sustained substantial damage. Flight and engine control continuity was established. A total of about 7 gallons of fuel was drained from the left fuel tank, and 1/8 to 1/4 cup was drained from the right fuel tank. There was no debris or discoloration noted with the fuel, and no damage to the fuel tanks or evidence of fuel leakage was discovered at the accident site. There was no evidence of fuel at the inlet side of the electrical fuel pump nor was there any remnants of fuel discovered at the outlet side of the engine driven fuel pump.
During postaccident interviews and correspondence, the pilot reported that he had not turned on the carburetor heat in the preceding 30 minutes before the engine failure and did not engage the lever after the failure. He also reported that both fuel gauges indicated levels just below half tanks about 45 minutes before his expected arrival time and estimated that each tank should have been about 1/3 to 1/2 full about the time of the loss of power.
Review of the FAA Carburetor Icing Chart found that the airplane was at risk of serious icing at glide power given the atmospheric conditions reported near the accident site. The airplane was retained for further examination.