Westland Lynx (Merged threads)
Iconoclast
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A point of view
To: Taff Missed
When I was working as a Reliability Maintainability consultant at Agusta on the A-129 I became aquainted with a Royal Navy officer on assignment at Agusta. He was the RN rep on the EH-101.
One day he asked me what I thought about the Rolls Royce engines used on the A-129. Trying to be diplomatic I told him that they were a good engine. He laughed saying that they were the same engines as used on the Lynx and that they were crap.
1. Engines
One day he asked me what I thought about the Rolls Royce engines used on the A-129. Trying to be diplomatic I told him that they were a good engine. He laughed saying that they were the same engines as used on the Lynx and that they were crap.
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That military Lynx thread was interesting - the Widow maker - I think that's a little harsh, but a name like that aint made up easy !! Poor SS got a right bashing there !! ( it's just a shame that mil post has turned into the traditional pprune slanging match ! )
Last edited by TheFlyingSquirrel; 29th May 2005 at 09:45.
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Lu,
Thirty years ago, when I first made acquaintance with the Lynx, the engines pi$$ed oil from the exhaust on shut down. To this day they still do it and the 'excuse' is that RR didn't realise that the engines would be mounted 5 deg nose up. They've had thirty years to put a px operated check valve in the PT brg feed.
To go back to the original question - 'Lynx' and 'reliability' is a contradiction in terms.
Taff
Thirty years ago, when I first made acquaintance with the Lynx, the engines pi$$ed oil from the exhaust on shut down. To this day they still do it and the 'excuse' is that RR didn't realise that the engines would be mounted 5 deg nose up. They've had thirty years to put a px operated check valve in the PT brg feed.
To go back to the original question - 'Lynx' and 'reliability' is a contradiction in terms.
Taff
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In more detail -
One of the problems was probably that there was no requirement for reliability or maintainability in the original spec.
Vibrations
For many years, Westlands would not let anyone do any mass balancing of the main rotor blades. The smoothest Lynx I flew had one blade that was one ounce different than the other three, whil I saw up to 8 oz of weight difference on opposite blades on a very rough machine - the blades weigh about 95 lb if I remember right, so 0.5% difference in weight is substantial. That was in the mid-80's, so I don't know about now.
AFCS
The story I heard was the money for the AFCS was mostly spent in development, and little was left over for buying the actual hardware, so missile gyros (renowned for long life) were used. I don't remember who did the AFCS for the military version, but Louis Newmarks (now Smith Newmarks) did the AFCS for the civil Westland 30, which did it's entire development and certification flight test without an AFCS problem. Does that tell you something about reliability of the AFCS?
Engines
Why the Lynx didn't have particle separation built in as standard (even on the Naval variant) was a substantial oversight on the part of MOD. The A129 has a particle separator and must be one of the reasons why the same engine works so well in that helicopter, but not in the Lynx.
And those are just the things I can remember 25 years later!
One of the problems was probably that there was no requirement for reliability or maintainability in the original spec.
Vibrations
For many years, Westlands would not let anyone do any mass balancing of the main rotor blades. The smoothest Lynx I flew had one blade that was one ounce different than the other three, whil I saw up to 8 oz of weight difference on opposite blades on a very rough machine - the blades weigh about 95 lb if I remember right, so 0.5% difference in weight is substantial. That was in the mid-80's, so I don't know about now.
AFCS
The story I heard was the money for the AFCS was mostly spent in development, and little was left over for buying the actual hardware, so missile gyros (renowned for long life) were used. I don't remember who did the AFCS for the military version, but Louis Newmarks (now Smith Newmarks) did the AFCS for the civil Westland 30, which did it's entire development and certification flight test without an AFCS problem. Does that tell you something about reliability of the AFCS?
Engines
Why the Lynx didn't have particle separation built in as standard (even on the Naval variant) was a substantial oversight on the part of MOD. The A129 has a particle separator and must be one of the reasons why the same engine works so well in that helicopter, but not in the Lynx.
And those are just the things I can remember 25 years later!
The biggest problem with the Gem engine was its oil distribution layout - the critical element was the white metal bearings in the reduction gearbox on the output shaft to the MRGB; they did not run without oil at all whereas the remaining bearings had a run-dry capability. So the reduction gearbox was the last location the oil went to before being scavenged which meant it was downstream of the filter. The filter had no bypass and blocked quite easily - the only indication you had was of the Oil pressure suddenly dropping from the green (stepped gauges) to the amber. If you didn't retard the SSL quickly the next thing that happened was the oil pressure dropping into the red followed by a large bang as the reduction gearbox seized. To my knowledge, this problem still exists despite several suggestions for modification and pilots are still having to shut engines down that, on inspection, are full of oil but have a blocked filter.
The only AFCS problem I encountered was the CAC (computer controlled acceleration) runaway; this happens in the collective channel when the accelerometers that are supposed to reduce collective pitch if they sense a rapid increase in 'g' go into a sort of open loop condition when the aircraft touches the ground and results in severe vertical oscillations (mine recorded +4.5 and - 1.5g on the g meter) - very exciting, especially when the CAC cutout is difficult to reach.
The only AFCS problem I encountered was the CAC (computer controlled acceleration) runaway; this happens in the collective channel when the accelerometers that are supposed to reduce collective pitch if they sense a rapid increase in 'g' go into a sort of open loop condition when the aircraft touches the ground and results in severe vertical oscillations (mine recorded +4.5 and - 1.5g on the g meter) - very exciting, especially when the CAC cutout is difficult to reach.
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FS;
Royal Navy Lynx down off Cornish coast, interesting report link in thread.
SS
That military Lynx thread was interesting - the Widow maker - I think that's a little harsh, but a name like that aint made up easy !! Poor SS got a right bashing there !!
Simulations carried out after the accident also suggest that crew believed they had no other option but to cut power to the rotor because of a perceived major incident rather than inadvertently descending into the sea.
SS
So we're probably back to tail rotor driveshafts again - there are not many reasons you would pull both speed selects at night over the sea but a TR drive failure is probably top of the list.
Purveyor of Egg Liqueur to Lucifer
FS,
Not a nose rubbing exercise I assure you. Merely a link from the 'widow maker' phrase that nobody likes and the most recent incident.
SS
RIP. They lost their lives trying to save others.
Not a nose rubbing exercise I assure you. Merely a link from the 'widow maker' phrase that nobody likes and the most recent incident.
SS
RIP. They lost their lives trying to save others.
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crab at SAAvn.co.uk, I take it you mean ECLs and not SSL? You have been away for a while though. 
I concur, one of the only reasons why I would wish to pull both back at night over the sea would be due to a percieved TR malfunction. Not nice.
Remember, its not been unknown for a sequence of events to unfold that the sim could never prepare a crew for. Leicester springs to mind.
SS, knowing what you knew before you started flying the Lynx- why did you?
Edited because crabs name kept coming up as a bloody email addy!
I concur, one of the only reasons why I would wish to pull both back at night over the sea would be due to a percieved TR malfunction. Not nice.
Remember, its not been unknown for a sequence of events to unfold that the sim could never prepare a crew for. Leicester springs to mind.
SS, knowing what you knew before you started flying the Lynx- why did you?
Edited because crabs name kept coming up as a bloody email addy!
Purveyor of Egg Liqueur to Lucifer
As the link has changed and the article is now in 'The Couriers' archives somewhere, I hope you don't mind me posting the news article here, for the benefit of those who have not yet had the chance to read it.
Fatal crash copter crew may have faced major fault
By Stefan Morkis
A ROYAL Navy inquiry into the cause of a helicopter crash that claimed the lives of two Dundee airmen has been unable to determine the reason for the accident.
However, their report suggests that the crew experienced a major malfunction and were forced to cut power to the helicopter’s rotor as they attempted to correct the fault.
The inquiry also found that it would be virtually impossible to recover from such a situation while flying at low level over the sea at night.
Pilot Lieutenant Robert Dunn (26), from Broughty Ferry, and naval aviator Lieutenant Jamie Mitchell (29), from Dundee, and two other crew members died when their Lynx helicopter came down off the coast of Cornwall last December.
They were carrying out a search and rescue mission around 17 nautical miles off Lizard Point when the helicopter crashed into the sea.
Despite interviewing 27 witnesses and examining radar data tapes and the technical accident investigation findings, the inquiry was unable to pinpoint the exact cause of the crash.
Its efforts have been hampered by the lack of any type of an accident data recorder, cockpit voice recorder—both of which were destroyed—or emergency radio report from the crew prior to the crash.
The inquiry has managed to determine the sequence of events that led up to accident.
The helicopter had been launched from HMS Portland at 6.20 pm on December 8 to assist in a search and rescue mission after HMS Montrose had reported a man overboard.
At 7.03 pm the helicopter descended to 100 feet above sea level as the crew searched and radioed in their position. After completing two orbits of a search pattern and about two minutes after reporting their position, the helicopter crashed.
Surveys of the wreckage of the helicopter on the seabed showed that although it was upright on the sea floor, it had suffered extensive damage.
Data from the aircraft’s radar tapes showed that when it hit the sea it had an extremely low forward speed but an extremely high rate of descent.
The initial investigation by the Royal Navy Flight Safety and Accident Investigation Centre indicated that neither of the helicopter’s engines was providing significant power to the rotor system at the time of the impact and that both appeared to have been shut down manually before the accident.
This action is known as a crash check and is extremely dangerous when flying at a low level over sea at night.
Therefore, the board of inquiry believes that the crew would only have taken this action if they had been firmly convinced they were dealing with a major emergency.
Simulations carried out after the accident also suggest that crew believed they had no other option but to cut power to the rotor because of a perceived major incident rather than inadvertently descending into the sea.
The inquiry was also unable to determine whether Lt Dunn was wearing his contact lenses when the helicopter crashed and so was unable to say whether this had been a contributory cause or not—thereby not completely ruling out the possibility of pilot error.
However, the inquiry did say that it was unlikely that a combination of disorientation and a minor malfunction had caused the crew to erroneously believe they had suffered a major malfunction.
The board of inquiry has made several recommendations in the wake of the crash, including that the RNFSAIC continues the investigation into the crash.
Wilma Donnelly, mother of Jamie Mitchell, said last night, “Whatever the inquiry finds will not bring my son back. The main concern of all the families was that there was no blame attached to anyone.”
Can we speculate now, as ;
Both engines manually shut down would certainly, as crab and wg13 mention, bring a tail rotor drive failure to the top of the suspects list.
edited because I've previously answered that question from wg13, dummy
Fatal crash copter crew may have faced major fault
By Stefan Morkis
A ROYAL Navy inquiry into the cause of a helicopter crash that claimed the lives of two Dundee airmen has been unable to determine the reason for the accident.
However, their report suggests that the crew experienced a major malfunction and were forced to cut power to the helicopter’s rotor as they attempted to correct the fault.
The inquiry also found that it would be virtually impossible to recover from such a situation while flying at low level over the sea at night.
Pilot Lieutenant Robert Dunn (26), from Broughty Ferry, and naval aviator Lieutenant Jamie Mitchell (29), from Dundee, and two other crew members died when their Lynx helicopter came down off the coast of Cornwall last December.
They were carrying out a search and rescue mission around 17 nautical miles off Lizard Point when the helicopter crashed into the sea.
Despite interviewing 27 witnesses and examining radar data tapes and the technical accident investigation findings, the inquiry was unable to pinpoint the exact cause of the crash.
Its efforts have been hampered by the lack of any type of an accident data recorder, cockpit voice recorder—both of which were destroyed—or emergency radio report from the crew prior to the crash.
The inquiry has managed to determine the sequence of events that led up to accident.
The helicopter had been launched from HMS Portland at 6.20 pm on December 8 to assist in a search and rescue mission after HMS Montrose had reported a man overboard.
At 7.03 pm the helicopter descended to 100 feet above sea level as the crew searched and radioed in their position. After completing two orbits of a search pattern and about two minutes after reporting their position, the helicopter crashed.
Surveys of the wreckage of the helicopter on the seabed showed that although it was upright on the sea floor, it had suffered extensive damage.
Data from the aircraft’s radar tapes showed that when it hit the sea it had an extremely low forward speed but an extremely high rate of descent.
The initial investigation by the Royal Navy Flight Safety and Accident Investigation Centre indicated that neither of the helicopter’s engines was providing significant power to the rotor system at the time of the impact and that both appeared to have been shut down manually before the accident.
This action is known as a crash check and is extremely dangerous when flying at a low level over sea at night.
Therefore, the board of inquiry believes that the crew would only have taken this action if they had been firmly convinced they were dealing with a major emergency.
Simulations carried out after the accident also suggest that crew believed they had no other option but to cut power to the rotor because of a perceived major incident rather than inadvertently descending into the sea.
The inquiry was also unable to determine whether Lt Dunn was wearing his contact lenses when the helicopter crashed and so was unable to say whether this had been a contributory cause or not—thereby not completely ruling out the possibility of pilot error.
However, the inquiry did say that it was unlikely that a combination of disorientation and a minor malfunction had caused the crew to erroneously believe they had suffered a major malfunction.
The board of inquiry has made several recommendations in the wake of the crash, including that the RNFSAIC continues the investigation into the crash.
Wilma Donnelly, mother of Jamie Mitchell, said last night, “Whatever the inquiry finds will not bring my son back. The main concern of all the families was that there was no blame attached to anyone.”
Can we speculate now, as ;
The initial investigation by the Royal Navy Flight Safety and Accident Investigation Centre indicated that neither of the helicopter’s engines was providing significant power to the rotor system at the time of the impact and that both appeared to have been shut down manually before the accident.
edited because I've previously answered that question from wg13, dummy
WG - quite right, ECLs not SSLs, I'm back on steam driven helicopters now.
If the Leicester one is the one I'm thinking of, I believe it had more to do with not reacting to an engine oil pressure dropping into the amber than anything else although their actions were completely in accordance with FRCs.
If the Leicester one is the one I'm thinking of, I believe it had more to do with not reacting to an engine oil pressure dropping into the amber than anything else although their actions were completely in accordance with FRCs.
Purveyor of Egg Liqueur to Lucifer
crab, I thought you had SSLs on the Sea King or is it an American-ism to call the ECLs SSLs 
I think wg is referring to this incident .
Three friends lost that day.
SS
I think wg is referring to this incident .
Three friends lost that day.
SS
SS, yes SSLs on the Sea King but ECLs on the Lynx - it took me a couple of years to switch over from PTIT to T6 and then the same back again.
Yes, that is the incident which highlighted the shortcomings in the FRC drills - see my previous post about engine oil pressure failures in the Lynx. If you don't assume the worst and retard the the ECL, the engine is very likely (as in this sad case) to blow up as the reduction gearbox seizes and the FPT shears. Investigation into most precautionary engine shutdowns on the Lynx reveals a full complement of oil but a clogging filter.
Yes, that is the incident which highlighted the shortcomings in the FRC drills - see my previous post about engine oil pressure failures in the Lynx. If you don't assume the worst and retard the the ECL, the engine is very likely (as in this sad case) to blow up as the reduction gearbox seizes and the FPT shears. Investigation into most precautionary engine shutdowns on the Lynx reveals a full complement of oil but a clogging filter.