Trust, But Verify

Maintenance is not finished until the paperwork is done. If it’s not, some tasks may not be complete, either.


One of the biggest challenges with which each aircraft owner must contend is maintenance. The FARs state the owner/operator is the party responsible for ensuring all applicable inspections and maintenance requirements are complied with for continued airworthiness. Typically, the owner/operator lacks certification to perform the required maintenance and inspections necessary for continued airworthiness and engages certificated mechanics and inspectors to perform the require tasks.

While the system usually works well, horror stories do arise. Logbooks go missing, what was scheduled to be a week-long annual inspection can turn into a months-long, expensive ordeal. Opinions differ on whether certain work is necessary or can be deferred, or is even appropriate. Regardless, each and every inspection and maintenance action is required to be entered into an appropriate record, which in turn is used to demonstrate the aircraft’s airworthiness.

Little training or knowledge of maintenance requirements is necessary to obtain a pilot certificate. Instead, the owner/operator generally depends upon trusted shops or mechanics to perform the necessary work and make the appropriate logbook entries.

The system works well—few aircraft fall out of the sky due to improper or incomplete maintenance. But “few” is not the same as “none.”  Importantly, owners/operators do have a readily available means to ensure required maintenance and inspections are performed: the aircraft’s maintenance records. Reviewing them can be an art, not a science, however, and the owner/operator often is left at the shop’s mercy when it comes to verifying specific tasks have been performed and determining the aircraft is airworthy in all respects. As we will discover, little things can mean a lot when it comes to verifying all maintenance work is accomplished and the associated paperwork complete.

On March 19, 2010, about 1910 Pacific daylight time, a Cirrus SR22 collided with trees and terrain during a forced landing following a loss of engine power near Morton, Wash. The airplane was substantially damaged. The private pilot was killed; the passenger sustained serious injuries. Visual conditions prevailed. The flight departed Concord, Calif., about 1540, destined for Renton, Wash.

The passenger later stated that, while the airplane was in cruise flight, the pilot suddenly placed his hands on the controls and told her the engine had lost power and they were going to land at a nearby airport. He entered a steep right turn toward the airport. The passenger could not recall hearing anything unusual at the time of the event. The pilot remained calm throughout the approach to the airport and reassured the passenger during the descent that they would land safely. The pilot also declared an emergency and spoke on the radio. The pilot did not attempt to activate the airframe parachute during the flight.

The airplane’s avionics included a function to record basic aircraft parameters. At 1857, the airplane began a shallow descent, fluctuating between 200 and 500 fpm. At 1904:16, the MFD data indicated a sharp reduction in EGT on all cylinders, accompanied by a gradual decrease in CHT. Engine speed decreased from the cruise value of approximately 2450 rpm and varied between 1200 rpm and 1750 rpm for the remainder of the recording.

At 1905:34, fuel flow spiked, decreased slightly and then pegged at 30 gph, the sensor’s maximum value, where it remained until the end of the recording. Indicated airspeed decreased to approximately 100 knots. The published best glide airspeed is 87 or 88 KIAS, depending on weight. However, additional glide range may be achieved with a windmilling propeller by increasing airspeed by five to 10 knots.

Based on the airplane’s position when the power loss occurred, an airport nine miles east would have been the nearest hard-surface runway. Several grass airstrips were to the west.

The airplane came to rest approximately 2.5 miles west-northwest of Strom Field Airport, Morton, Wash., in a rural residential area. The wings and forward fuselage area sustained significant impact damage. All control surfaces remained attached. There was no fire. Approximately seven gallons of fuel were drained from the left wing fuel tank. The right fuel tank was breached. Investigators obtained approximately one cup of fuel from the right header fuel tank following removal of the wreckage from the accident site.

The engine’s throttle and metering assembly inlet fitting cap, p/n 639494, was located on the number 1 and 3 intercylinder baffle. There was no evidence of damage to the cap. There was evidence of light blue staining on the crankcase. Testing showed that with the fuel inlet cap installed finger-tight, engine operation was normal and did not reveal any abnormalities preventing normal operation and production of rated horsepower.

In January 2010, the airplane underwent an annual inspection. The shop’s director of maintenance later indicated the inspector assigned to the aircraft should have signed off the inspection and maintenance endorsement for the airplane logbooks but overlooked doing so. Several items on the shop’s inspection checklist for the accident airplane were not complete, including checks of the engine’s fuel injection system and final inspection/return to service. Investigators concluded the annual inspection was never completed.

Probable Cause
The NTSB determined the probable cause(s) of this accident to include: “The failure of maintenance personnel to properly secure a fitting cap on the throttle and metering assembly inlet after conducting a fuel system pressure check, which resulted in a loss of engine power due to fuel starvation. Contributing to the accident was the decision by the director of maintenance to return the airplane to service without verifying with the assigned inspector that all annual inspection items had been completed.”

Some two months after the shop visit, the airplane lost power and crashed because the inlet fitting cap—a component not normally inspected by the pilot during a pre-flight—wasn’t properly torqued. The shop released the airplane before all work was finished. Lack of a logbook endorsement returning the airplane to service would have been the owner/operator’s only clue that the annual inspection wasn’t complete.




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