Re: Google video crash...
I have always felt that understanding accidents leads to fewer accidents. We know the results of the Caribou crash and if we understand the causes, we will make sure that we don't make the same mistake. It is exactly as Randy said.
Here is a narrative of the accident from a 2001 Austrailasian Air Safety Seminar by James Donnelly. The text goes into some graphic detail and I have chosen to include it below because it may be hard to spot on the PDF link (apologies for the excess "." and lack of " ' " formatting you know).
Gust lock... starting on page 7 at http://www.asasi.org/papers/2001/Fou...0Accidents.pdf
The final example I.d like to bring before you today also deals with a modified aircraft. Like the first event I described, it.s unusual because virtually the entire accident sequence is captured on videotape.
The accident occurred in August 1992 at the Gimli Industrial Park in Manitoba.a famous site in Canadian aviation history, where an Air Canada Boeing 767 known as the Gimli Glider was dead-sticked onto a drag racing strip, following fuel exhaustion.
The accident aircraft is a highly modified de Havilland aircraft. In this case a Caribou had been converted to turbine power and was operated under the EXPERIMENTAL category of CAR 4b.
The conversion was accomplished at Gimli, and the aircraft first flew in mid-November 1991, before accumulating about 23 hours on 12 flights by month end.
These preliminary tests revealed the need for the replacement of the aircraft.s mechanical vacuum pumps with a Bendix suction system, the addition of in-line fuel boost pumps and the installation of a newly designed hydraulic pump.
The accident occurred on August 27, 1992 on the first of several planned trips to flightcheck the fuel and hydraulic systems. The aircraft had been hangared in a partially disassembled state over the winter, and had only recently been re-assembled, including the re-installation of the complete tail section.
I.ll let the video show you what happened.and I will caution you right now that this footage is extremely graphic.
The accident investigation used this videotape and some 35mm photographs as a key resource in determining what went wrong at Gimli.
With the exception of a slightly higher-than-normal nose attitude at lift-off, the aircraft.s initial climb appeared normal. At about 35 feet AGL, the aircraft made a noticeable pitchup movement.
When I tell you that the photography revealed that the elevator control surfaces were observed to pitch trailing-edge-up for rotation, neutralize and then remain in the neutral position through the balance of that short flight, I expect most of you will come to the same conclusion as the Transportation Safety Board of Canada. The aircraft.s control gust locks were at least partly engaged.
A very close examination of the video does indicate rudder movement and minimal elevator movement, during the start of the takeoff roll.
On the standard Caribou, the gust lock control handle is located forward of the power quadrant, and it has two positions.forward for Unlocked, and aft for Locked. If the control surfaces are not in the neutral position when the lock is engaged, any movement of the surfaces through the neutral position will cause the lock to engage.
In addition, on the factory-standard Caribou, the control handle is designed so that when it is in the aft-Locked position, the power levers cannot be fully advanced. This is intended to prevent power application and takeoff when the gust lock system is engaged. The accident investigation further revealed that the aircraft.s takeoff distance was approximately 20 per cent longer than anticipated for the conditions. This may provide further evidence that the gust locks played a part in this event.
Analysis of the recovered debris indicated that, although the aileron and elevator locking mechanisms were in their respective Disengaged positions, the rudder locking mechanism was found to have been in the fully engaged position at impact.
Further investigation revealed that in fact, it had been jammed there by the forces of the impact. In addition, the analysis determined from the damage evidence that the aileron control lock had been dis-engaged at the time of impact.
In its synopsis of the accident, the Transportation Safety Board concluded that the control gust lock system had not been fully disengaged prior to flight and that one or more of the locking pins had become re-engaged after lift-off.
What could have prevented this accident? The most obvious solution was that a complete six-point control check prior to takeoff would have revealed that free and proper movement of the control system was compromised.
No control check was seen by witnesses on the ground, nor was one recorded on video or still photography. As noted earlier, some rudder and elevator movement was observed, at the end of the runway at the start of the takeoff roll.
The Caribou.s standard procedures do allow for locking the control surfaces for ground operation, but the aircraft flight manual also requires a six-point control check prior to takeoff.
Another point.although not one addressed by the TSB in its review concerns the crew. We understand that shortly before the flight, the scheduled co-pilot.a very experienced piston-Caribou captain.was replaced by another pilot with considerably less total time and experience on type. He was, in fact, the aircraft owner.s son.
We therefore speculate whether a more experienced co-pilot might have caught the missed six-point control check, or might have been more aware that the aircraft was not responding as it should have.
During the post-accident autopsy, a knob from the gust lock handle was found embedded in the captain.s right wrist. The TSB concluded that the captain was attempting to operate the gust lock handle when the aircraft hit the ground.
Our expectation was that the pilot flying would have had his hand on the power lever quadrant, which is located immediately aft of the gust lock handle. It is therefore conceivable that, during the impact sequence, his hand might have moved forward, and that this might account for the autopsy finding.
This accident investigation was problematic for us as the aircraft.s original manufacturer, as we had not been involved in the turbine conversion, system modifications, or subsequent flight testing.
As I noted earlier, the conversion required extensive modification of a large number of the aircraft.s systems, and we know from the investigation that these included a redesigned throttle quadrant.
The TSB report concludes that the newly designed system did not interfere with the positional relationship between the throttle levers and the gust lock control handle, as full power could not be obtained with the lock handle in the engaged position. However, in our minds, since we did not design or participate in the modification process, we cannot conclusively rule-out interference with normal operation of the aircraft.s original systems.
In this accident investigation our contribution was therefore essentially limited to the identification of components familiar to us, confirming the operation of the original gust lock system, and confirming the deflection of the control surfaces. spring tabs when operation is attempted against the locks.
We had not reviewed the turbine aircraft flight manual but here again, we suspect it was substantially similar to the original aircraft flight manual.
The original manufacturer.s ultimate responsibility in an accident involving a heavily modified aircraft has not yet.at least to my knowledge.been fully delineated. This remains a very problematic issue, as the original manufacturer may be implicated. at least in the early stages.of lawsuits arising from an accident.
This may be as a result of a .deep-pockets. strategy by plaintiffs or as a result of a legitimate concern over product liability issues.
Regardless of the motivation, however, we have to recognize that modifying an aircraft substantially from its original configuration poses risks and unforeseeable challenges which are far more extensive.and therefore potentially much more dangerous.than simply beefing-up, or swapping the engine in a sports car.
And of course, the more sophisticated the aircraft, the more complex the systems and the analysis required to ensure safety of flight.
------
Thank you for your time today.
Jim Donnelly began his aviation career flying commercial helicopters in the
Canadian Arctic in the early 1970s. In 1979 he was employed by the de Havilland Aircraft of Canada as a Field Service Representative and lived for six years in various locations worldwide, including: Monterey, California, Port Moresby, Papua New Guinea, Sana.a, North Yemen and Barranquilla, Colombia. In 1986 he joined the Air Safety Group of Boeing Canada, de Havilland Division. Jim is currently Manager, Product Safety, Bombardier Aerospace, Regional Aircraft, based in Toronto, Ontario Canada. His responsibilities include providing assistance to government authorities investigating aircraft accidents involving de Havilland Canada aircraft (DHC-2 Beaver, DHC-3 Otter, DHC-4 Caribou, DHC-5 Buffalo, DHC-6 Twin Otter, DHC-7 Dash 7 and DHC-8 Dash 8) as well as those
involving the Canadair Regional Jet airliner (CL600-2B19).
I have always felt that understanding accidents leads to fewer accidents. We know the results of the Caribou crash and if we understand the causes, we will make sure that we don't make the same mistake. It is exactly as Randy said.
Here is a narrative of the accident from a 2001 Austrailasian Air Safety Seminar by James Donnelly. The text goes into some graphic detail and I have chosen to include it below because it may be hard to spot on the PDF link (apologies for the excess "." and lack of " ' " formatting you know).
Gust lock... starting on page 7 at http://www.asasi.org/papers/2001/Fou...0Accidents.pdf
The final example I.d like to bring before you today also deals with a modified aircraft. Like the first event I described, it.s unusual because virtually the entire accident sequence is captured on videotape.
The accident occurred in August 1992 at the Gimli Industrial Park in Manitoba.a famous site in Canadian aviation history, where an Air Canada Boeing 767 known as the Gimli Glider was dead-sticked onto a drag racing strip, following fuel exhaustion.
The accident aircraft is a highly modified de Havilland aircraft. In this case a Caribou had been converted to turbine power and was operated under the EXPERIMENTAL category of CAR 4b.
The conversion was accomplished at Gimli, and the aircraft first flew in mid-November 1991, before accumulating about 23 hours on 12 flights by month end.
These preliminary tests revealed the need for the replacement of the aircraft.s mechanical vacuum pumps with a Bendix suction system, the addition of in-line fuel boost pumps and the installation of a newly designed hydraulic pump.
The accident occurred on August 27, 1992 on the first of several planned trips to flightcheck the fuel and hydraulic systems. The aircraft had been hangared in a partially disassembled state over the winter, and had only recently been re-assembled, including the re-installation of the complete tail section.
I.ll let the video show you what happened.and I will caution you right now that this footage is extremely graphic.
The accident investigation used this videotape and some 35mm photographs as a key resource in determining what went wrong at Gimli.
With the exception of a slightly higher-than-normal nose attitude at lift-off, the aircraft.s initial climb appeared normal. At about 35 feet AGL, the aircraft made a noticeable pitchup movement.
When I tell you that the photography revealed that the elevator control surfaces were observed to pitch trailing-edge-up for rotation, neutralize and then remain in the neutral position through the balance of that short flight, I expect most of you will come to the same conclusion as the Transportation Safety Board of Canada. The aircraft.s control gust locks were at least partly engaged.
A very close examination of the video does indicate rudder movement and minimal elevator movement, during the start of the takeoff roll.
On the standard Caribou, the gust lock control handle is located forward of the power quadrant, and it has two positions.forward for Unlocked, and aft for Locked. If the control surfaces are not in the neutral position when the lock is engaged, any movement of the surfaces through the neutral position will cause the lock to engage.
In addition, on the factory-standard Caribou, the control handle is designed so that when it is in the aft-Locked position, the power levers cannot be fully advanced. This is intended to prevent power application and takeoff when the gust lock system is engaged. The accident investigation further revealed that the aircraft.s takeoff distance was approximately 20 per cent longer than anticipated for the conditions. This may provide further evidence that the gust locks played a part in this event.
Analysis of the recovered debris indicated that, although the aileron and elevator locking mechanisms were in their respective Disengaged positions, the rudder locking mechanism was found to have been in the fully engaged position at impact.
Further investigation revealed that in fact, it had been jammed there by the forces of the impact. In addition, the analysis determined from the damage evidence that the aileron control lock had been dis-engaged at the time of impact.
In its synopsis of the accident, the Transportation Safety Board concluded that the control gust lock system had not been fully disengaged prior to flight and that one or more of the locking pins had become re-engaged after lift-off.
What could have prevented this accident? The most obvious solution was that a complete six-point control check prior to takeoff would have revealed that free and proper movement of the control system was compromised.
No control check was seen by witnesses on the ground, nor was one recorded on video or still photography. As noted earlier, some rudder and elevator movement was observed, at the end of the runway at the start of the takeoff roll.
The Caribou.s standard procedures do allow for locking the control surfaces for ground operation, but the aircraft flight manual also requires a six-point control check prior to takeoff.
Another point.although not one addressed by the TSB in its review concerns the crew. We understand that shortly before the flight, the scheduled co-pilot.a very experienced piston-Caribou captain.was replaced by another pilot with considerably less total time and experience on type. He was, in fact, the aircraft owner.s son.
We therefore speculate whether a more experienced co-pilot might have caught the missed six-point control check, or might have been more aware that the aircraft was not responding as it should have.
During the post-accident autopsy, a knob from the gust lock handle was found embedded in the captain.s right wrist. The TSB concluded that the captain was attempting to operate the gust lock handle when the aircraft hit the ground.
Our expectation was that the pilot flying would have had his hand on the power lever quadrant, which is located immediately aft of the gust lock handle. It is therefore conceivable that, during the impact sequence, his hand might have moved forward, and that this might account for the autopsy finding.
This accident investigation was problematic for us as the aircraft.s original manufacturer, as we had not been involved in the turbine conversion, system modifications, or subsequent flight testing.
As I noted earlier, the conversion required extensive modification of a large number of the aircraft.s systems, and we know from the investigation that these included a redesigned throttle quadrant.
The TSB report concludes that the newly designed system did not interfere with the positional relationship between the throttle levers and the gust lock control handle, as full power could not be obtained with the lock handle in the engaged position. However, in our minds, since we did not design or participate in the modification process, we cannot conclusively rule-out interference with normal operation of the aircraft.s original systems.
In this accident investigation our contribution was therefore essentially limited to the identification of components familiar to us, confirming the operation of the original gust lock system, and confirming the deflection of the control surfaces. spring tabs when operation is attempted against the locks.
We had not reviewed the turbine aircraft flight manual but here again, we suspect it was substantially similar to the original aircraft flight manual.
The original manufacturer.s ultimate responsibility in an accident involving a heavily modified aircraft has not yet.at least to my knowledge.been fully delineated. This remains a very problematic issue, as the original manufacturer may be implicated. at least in the early stages.of lawsuits arising from an accident.
This may be as a result of a .deep-pockets. strategy by plaintiffs or as a result of a legitimate concern over product liability issues.
Regardless of the motivation, however, we have to recognize that modifying an aircraft substantially from its original configuration poses risks and unforeseeable challenges which are far more extensive.and therefore potentially much more dangerous.than simply beefing-up, or swapping the engine in a sports car.
And of course, the more sophisticated the aircraft, the more complex the systems and the analysis required to ensure safety of flight.
------
Thank you for your time today.
Jim Donnelly began his aviation career flying commercial helicopters in the
Canadian Arctic in the early 1970s. In 1979 he was employed by the de Havilland Aircraft of Canada as a Field Service Representative and lived for six years in various locations worldwide, including: Monterey, California, Port Moresby, Papua New Guinea, Sana.a, North Yemen and Barranquilla, Colombia. In 1986 he joined the Air Safety Group of Boeing Canada, de Havilland Division. Jim is currently Manager, Product Safety, Bombardier Aerospace, Regional Aircraft, based in Toronto, Ontario Canada. His responsibilities include providing assistance to government authorities investigating aircraft accidents involving de Havilland Canada aircraft (DHC-2 Beaver, DHC-3 Otter, DHC-4 Caribou, DHC-5 Buffalo, DHC-6 Twin Otter, DHC-7 Dash 7 and DHC-8 Dash 8) as well as those
involving the Canadair Regional Jet airliner (CL600-2B19).
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