Piper PA-24-250 N7538P accident near North Kingstown, Rhode Island

Probable cause

A total loss of engine power during final approach due to the pilot’s failure to recognize that the environmental conditions were susceptible to carburetor icing and apply carburetor heat, which resulted in the formation of carburetor ice. Contributing to the accident was the low altitude at which the pilot recognized the loss of engine power, reducing the amount of time to troubleshoot and address the problem.

NTSB analysis

While about 5 miles from the destination airport and maneuvering the airplane for a straight-in approach to the runway, the pilot began performing the prelanding checklist items, which included turning on the electric fuel pumps. When the flight was about 1/2 to 1 mile from the runway and about 800 ft above ground level (agl), the pilot recognized that the airplane was low, so she increased the throttle, but the engine did not respond. She verified that the mixture was full rich and that the fuel selector was on the fullest tank, and she checked the magnetos but did not apply carburetor heat. She observed a total loss of engine power, declared an emergency to the tower controller, prepared for ditching (because the flight was over water while on the approach), and ditched the airplane into the water below.

Postaccident examination of the airplane revealed no preimpact failure or malfunction of the engine powertrain, ignition, or lubrication systems. Foreign debris was found inside the inlet section of the engine-driven fuel pump. Although this material matched the composition of inner layer material of a fuel supply hose, none of the fuel supply hoses recovered from the airplane’s engine compartment were found to be missing any section of the inner layer. Also, because the two electric fuel pumps that were on during the approach could allow fuel to bypass the engine-driven fuel pump in the event of its obstruction or failure, the foreign material likely did not contribute to the total loss of engine power.

Although environmental conditions at the time of the accident were conducive to the formation of carburetor ice at cruise and glide power, the pilot did not recognize that or apply carburetor heat during any portion of the descent, or after the loss of power. Thus, it is likely that, during the approach, carburetor ice accrued when the engine was operating at a reduced power setting (consistent with glide power), resulting in the total loss of engine power.

Also, although the airplane’s engine failure checklist specified applying carburetor heat, the low altitude at which the pilot recognized loss of engine power significantly reduced the amount of time available to troubleshoot and restore engine power to prevent the ditching.

Text from the NTSB. Open the NTSB docket for ERA24LA164 for the full record.