Piper PA32RT N543GS accident near Selma, Alabama

Probable cause

The mechanic’s failure to clean the oil suction screen during the most recent maintenance, which resulted in oil starvation and subsequent total loss of engine power.

NTSB analysis

After departure, the pilot leveled the airplane at a cruise altitude of 15,000 ft mean sea level (msl). About 40 minutes into the flight, the pilot reported an engine "fluctuation" to the controller and requested to divert to a nearby airport. The controller cleared the airplane for the diversion, and the pilot indicated that the propeller was turning; however, the airplane had experienced a total loss of engine power and then an in-flight fire. When the airplane was about 3 miles from the diversion airport and about 3,100 ft msl, radar and voice communications were lost. The airplane impacted a field, and all components of the airplane were within the vicinity of the main wreckage.

Examination of the engine revealed a hole in the top of the crankcase, thermal discoloration on the aft section of the crankshaft, and detachment of the No. 6 connecting rod from the crankshaft journal. The No. 6 rod journal exhibited severe thermal discoloration. Examination of the connecting rod journal bearings revealed extensive damage to all the submitted bearings. Circumferential score marks and heavy wear were visible on the inner diameter of the bearing halves. The camshaft was fractured in torsional overstress.

The oil sump was removed from the engine and contained oil, metallic particles, small carbon chips, and organic debris. The oil filter was removed, disassembled, and a small amount of carbon chips and metallic debris was noted on the filter. The oil pump was removed from the accessory section of the engine and the pump body exhibited scoring. In addition, the oil suction screen was completely occluded by debris that filled the screen over 60% and likely starved the engine of oil. Examination of the debris in the oil suction screen revealed that approximately 75% of the debris was metallic and the remaining 25% of the debris was not metallic.

Given the significant amount of nonmetallic debris, it likely accumulated over time and resulted in the engine being starved of oil. When the engine subsequently lost total power, the crankcase was penetrated, which is likely the origin of the in-flight fire.

There was no record that the oil suction screen was cleaned during the airplane’s most recent oil change about 3 months before the accident. The last documented cleaning of the oil suction screen was about 11 years before the accident and the engine had accumulated an additional 550 hours until the time of the accident.

The engine's operating manual stated that "at each fifty hours inspection,” the oil suction and oil pressure screens should be removed and inspected for metal particles, cleaned and reinstalled. It also noted that, “on installations employing external oil filters,” inspection of the oil suction screen “should be observed at the 100-hour inspection.” Furthermore, the airframe service manual stated that the oil suction screen should be cleaned at every 50-hour interval.

When asked if the oil suction screen was cleaned during the oil change associated with the most recent annual inspection, the mechanic who performed the work stated that the oil cooler was cleaned, which likely indicates that the oil suction screen was not cleaned. A discrepancy for low oil pressure that was recorded in the engine maintenance log the day before the accident was likely due to the obstructed oil suction screen. Subsequently, the obstructed oil suction screen led to the engine being starved of oil and a total loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA20LA212 for the full record.