According to the pilot of the Glasair II, when the plane was in cruise flight near Spanish Fork, Utah, it experienced fuel flow problems. He activated the fuel system boost pump, putting it on the high-boost setting.
As he neared the destination airport, the engine quit. The airplane did not have enough altitude to glide to the runway, so he performed a forced landing in a field about 1,500 feet from the runway.
During the landing roll, the plane nosed onto its back hard enough to tear the wings off. The pilot was slightly injured.
A post-accident examination revealed that the electric boost pump would operate when the high-boost switch was selected. However, when the low-boost switch was selected, it would not operate due to a malfunctioning resistor.
Further testing revealed that when the electric boost pump was turned off and the engine-driven pump was trying to draw fuel without the use of the electric boost pump, the electric boost pump introduced air into the fuel system through a worn shaft on the pump. Investigators determined that air would likely hinder the engine-driven pump from producing enough suction and starve the engine of fuel.
The NTSB determined the probable cause of the accident was a loss of engine power due to fuel starvation, which likely resulted from air being introduced into the fuel system through the worn shaft of an electric fuel boost pump.
NTSB Identification: WPR13LA147
This March 2013 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
How did the pilot survive if the wing was torn off? The lap belt is attached to the wing. Would tear the pilot out of the plane.
Upon reading the full NTSB narrative, I see that the pilot’s lap belt “fractured.” That was fortunate for the pilot – otherwise he would have been drawn and halved.
Thank You Meg, for listing the NTSB link. I fly a Mooney 201 with a lot more hours than the Glasair. From the link
” ADDITIONAL INFORMATION
Following the accident, the pilot had the following electric fuel pumps bench tested: the accident pump and another Duke, Inc. pump that he had installed on a Mooney 231, which was equipped with a similar engine. Both of them passed the bench test and no anomalies were noted. After installing both pumps back on the same engine (one after the other), it was noted that fuel was still inhibited from reaching the engine-driven fuel pump or developing full pressure.
There were no blockages in lines, filters, gascolator, and fuel selector. Disconnecting the output hose from the pump and attaching a clear vinyl hose revealed that a steady stream of air bubbles was produced from the electric pump. Upon further testing, he found that the pump introduced air into the fuel line when not pressurizing the output, or when the pump was turned off but under suction, as would happen with the engine-driven pump trying to draw fuel without the use of the electric boost pump. After overhauling the pumps with a new shaft bearing and seal, he has had no problems with the fuel system or engine in indication the shaft and seals were worn. He opined that the air leak originated from the shaft on both pumps and that the engine-driven pump could not produce enough suction with introduction of air in the system. ”
The rest of the NTSB write up is very much worth reading. Fascinating, the pilot was the one who dug deep enough to get the cause. Not the FAA, Not the NTSB, Not CMI, Not DUKES.
Sorry for mentioning the FAA, it’s not their job. But I wonder when they will stop using morse code and jibberish coded weather reports. Bandwidth isn’t a problem in 2015.
The NTSB report has a couple of inconsistencies. First, the explanation about the boost pump not operating on the low setting is irrelevant if the high setting was selected as the pilot claimed. Next, AFAIK, it is common for Glasair pilots to turn off the boost pump after reaching cruise altitude and not turn it back on till descending to pattern altitude at the destination. Thus, if there was any “air in the system” problem, it should have manifested itself by rough running long before the accident.
Early Glasair plans called for a header tank. The header tank fuel pickup was slightly higher than the fuel entry port on the engine-driven pump (on carburated engines) with the result that there was some head pressure to push fuel through the system even without the boost pump if the header tank was selected. This KISS-principle may have been abandoned in later, more sophisticated Glasairs as the occasional stink of fuel in the cockpit and/or the need for more space behind the panel caused builders to forgo a header tank in favor of more fuel bays in the wing.
Finally, while this is a nit-pick, Glasairs (not Glastars) have a single wing structure based on a composite I-beam extending from one wingtip to the other. Accordingly, “the wings” did not depart the formation during the nose over, only “the wing”.
Glad my fellow Glasair pilot survived the incident but his aircraft was almost certainly a write-off.