Five Deaths Demand Justice Petition

[dhc2widow]

PS. Because of the following letter, TCCA issued this: http://www.tc.gc.ca/civilaviation/ce...ry/2007-02.htm

To Whom it may concern.

As a Aircraft Maintenance Engineer with 28 years of experience working on DHC-2’s, and having been involved with the Ministers Delegate Maintenance program for 6 years, I have been asked by the family members of the victims of the fatal accident of DHC-2 C-GAQW to inspect the retrieved aircraft and submit a report on my observations with respect to causative factors of this accident. I also have possession of video taken at the site as well as of the recovery process which I have reviewed.

On April 28, 2006 I attended the storage locker where the aircraft has been kept, in dry secure storage. The recovered portions of the aircraft included both floats, empennage, LH wing and flight controls, and the fuselage including the engine mount, engine accessory section. Sections remaining at the accident site would include the RH wing, engine power section, propeller and cowlings. The power section did not come up with the accessory section due to magnesium construction of the blower/ intake section having corroded away due to salt water emersion.

Most of the aircraft has a layer of organic growth due to being submerged for some period of time. Due to the storage conditions this growth is now dried up. Immediately apparent is the fact the windscreen, lower inboard section of the left wing, the right side of the fuselage including approximately 1 foot up the side of the vertical fin, as well as the right inboard leading edge of the horizontal stabilizer, have been covered with engine oil. This pattern of oil leakage is consistent with a major oil leak suddenly developing in flight, concentrated on the right side due to prop wash, which adheres to the colder dry surface of the aluminum, and is not easily removed. Subsequent to the accident, oil would be very unlikely to stick to the surfaces as they would be wet with water, and the oil contamination pattern would not be so well defined.

The aircraft damage viewed would suggest the mechanics of the accident involved a forced landing due to lack of visibility through the aircraft windscreen compounded by poor visibility due to meteorological conditions at the time. A power off nose up attitude would produce a rapid decent with a heavily loaded aircraft. The aft section of the RH float is bent up, with suggests a heal dig which would have bounced the aircraft back into the air. A slight kink in the upper LH wing half way between the strut and tip, plus the tip being knocked off in an upward motion suggest the LH wing may have contacted the water at some point in the chain of events. The most significant damage appears to have been caused by the aircraft subsequently stalling and striking the water in a nose and RH wing down attitude with a sideways component to the direction of travel. Both upper diagonal tubes of the engine mount have tension fractures (are completely separated mid tube), and both lower mount tubes have compression bulges just above the firewall mount, indication a significant vertical inpact The forward section of the right float has basically exploded from the impact of being driven up and being struck by the propeller and impact with the water. At the same instant the right wing impacted the water and was torn from the fuselage, as indicated by upper cabin damage. Video shows the right wing on the bottom with a near 90 degree bend upward, just outboard of the outer flap attach, also what appears to be the exhaust intensifier tube is completely flattened by the impact. Compression damage to the left mid section of the fuselage suggests the aircraft struck the water with a sideways component consistent with a stall.

I do not believe the aircraft cart wheeled into the water as there is very little damage to the Left wing, the horizontal stab, elevators, or rudder and vertical fin as viewed in underwater video. Damage to the fin, rudder, and elevator tip was incurred during salvage.

Based on my experience and my observation of the aircraft I would conclude that the initiating cause of this accident was a failure of one of the upper cylinders, or given the amount of oil and the short duration of the flight, a failure of the cylinder base studs. I support this with reference to the Transport Canada Service Difficulty Reporting Data base www.tc.gc.ca/wsdrs/ quick search of Pratt & Whitney R-985-AN 14 and 14B, between April
of 2000 and today shows 99 service difficulty reports were submitted related to cylinders and power section problems. Of these 39 were related to Cylinder cracking or complete head separation. 9 incidents were
reported of cylinder base stud failures. The remaining reports included cracked crankshafts, cracked cases, cracked or broken pistons, and broken or bent connecting rods. These are only reported incidents, more are likely to have occurred which are not reported.

Several problems can create the circumstances for these types of failures. Most of these cylinders are old and are heat cycle fatigued; they may have been overhauled several times, and are subject to mandatory ultrasonic testing at overhaul, as well as a visual inspection every 100 hrs. Unfortunately many cylinders continue to fail, even within 50 hrs after the UT testing has been completed. Often the visual inspections can miss crack indications due to oil staining and difficulty in accessing the full circumference of the cylinder head area. It is my belief that a crack can start internally within the head and progress into a complete head separation in far less than the 100 hrs specified in the inspection requirement. As these are supercharged engines another factor may be over boosting an engine (too much manifold pressure for the given engine rpm). This is not common or likely with experienced pilots.
The third and most troubling possibility is the use of substandard parts. As these engines are so old, many of the parts are now being made by after market suppliers, referred to as FAA-PMA. Such parts are suppose to be equal to the original manufactures parts, however this is not always so. Items such as cylinder base studs could easily fall into this classification.

In light of this information I would consider a review of the engine technical logs to identify if any cylinders have been replaced due to cracking, or if any base studs have been replaced due to failing. This would be indicative of the overall condition this engine at the time of the accident.

Given the number of reported occurrences of these types of failures, that in my opinion has a very high probability of being what initiated the unfortunate chain of events that lead to the death of the occupants of C-GAQW, I believe that the recovery of the power section of this engine for more detailed investigation should be essential in ensuring safety for the large number of people in remote locations who travel in aircraft equipped with these engines. Further, a fair question to be asked would be to inquire what follow up investigations have been carried out with respect to the 9 instances of cylinder base stud failure reported, and what actions have been initiated to reduce these occurrences.

As part of my review I have a copy of Bill Yearwood’s letter to Ms. Larcombe at the Chief Coroners office related to this accident, dated September 21, 2005. With respect to comments related to TSB’s examination of the wreckage on July 29, 2005. I would like to forward two comments which may have a bearing on the conclusions arrived at. First, the statement that the engine mounts were in place and showed no sign of impact damage is contrary to my observations as noted above. At the retrieval the aircraft was upside down which would have made the damage I observed very difficult to detect. Second, the propeller control was set to fine pitch. This position according to the DHC-2 flight manual is used for take off, prior to landing, and in the event of an engine failure. Had the pilot flown into the water would the prop control not have been pulled back to 1850 rpm, the recommended cruise setting?

This concludes my observations and comments. In the interest of public safety I would be happy to discuss this matter with anyone concerned.

Respectfully