Can You Help?

The UK Air Accidents Investigation Branch can narrate a story so well, that we like bringing you excerpts, in their own words, to illustrate "things from which we can learn." Here's an example:

Some 15 minutes in to the flight, the pilot noticed a slight reduction in engine power. Almost immediately, a significant amount of blue smoke entered the cabin. As the visibility reduced, the pilot elected to make a forced landing, but before he could shut the engine down, it seized. Following this, the smoke dissipated but the aircraft suffered extensive damage as it landed in a field. Examination of the aircraft revealed clear evidence of loss of engine oil in flight, but despite a detailed strip examination of the engine, the origin of the leak was not established. Prior to flight, the pilot had checked the oil level and between 7 and 8 quarts were indicated on the dipstick.

...Following an uneventful take off and climb to 4,000 feet, the pilot checked the engine temperatures and pressures and found them to be in the normal range. Some 15 minutes into the flight he noticed a slight engine power loss and this was immediately followed by a significant amount of blue smoke entering the cabin from the right and centre at about windscreen height.

As the smoke increased in intensity, the visibility reduced within the cockpit and so the pilot elected to shut down the engine and carry out a forced landing. As he selected the engine mixture to idle cut off, a “click, click” noise was heard from the engine, which then seized... The pilot was now committed to a forced landing...

"Well, we're here," someone was heard to have said:

Whilst on the 45° approach leg the pilot felt he was too high and needed to lose height, and so he attempted to achieve this by selecting the landing gear down. However, he now found it increasingly difficult to maintain the required glide airspeed of 85 kt and so turned directly in to the field. Following the turn, and once the boundary hedge of the field had been cleared, the flaps were fully deployed but, with the aircraft now at about fifty feet above the ground, the rate of descent increased rapidly. In an attempt to regain airspeed and subsequently to arrest the rapid rate of descent, the pilot pushed the nose of the aircraft down. Just prior to the touchdown a flare was initiated, at which point the aircraft landed heavily. The landing gear absorbed most of the impact but then collapsed.

Once G-RJCP came to a halt the pilot and his passenger, who were wearing lap and diagonal harnesses, left the aircraft, unhurt, using doors which had already been unlatched during the final approach to the field.

So, what the heck happened?

On inspection, it was readily apparent that the engine had a large hole in the top of the crankcase close to number four cylinder position, and so it was removed from the airframe to facilitate a strip examination at an engine overhaul facility, under the supervision of the AAIB. It had suffered a catastrophic failure, was totally seized and the large hole in the top of the crankcase above the number four cylinder had been caused by the number four connecting rod becoming detached from its piston and then being forced upwards. The engine generally exhibited signs of overheating, consistent with operating with a lack of oil...

E xcept, we need a punchline. Here's the best the evidence would yield:

Despite extensive examination of the engine and the aircraft the cause of the oil loss in flight was not established.

If you're of an inquiring mind, you might want to see if they missed something. The whole report is at the link below.

FMI: www.aaib.dft.gov.uk/bulletin/apr03/grjcp.htm