Jervis Bay helicopter crash
The NSCA, what an amazing capability and service it was
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Not super familiar with NH-90, is an uncontained engine failure very common for the RTM-322 engine used in this aircraft or has there been some embellishment as the story is told/retold by some that don’t know the real story? It seems this failure mode on modern turbine engines is becoming pretty rare.
I ask only because my myself and my crew once experienced an engine failure due to a ruptured combustion liner(on a T700-700) and by the time the final report was issued 6 months later everything we had in our incident statements was either left out of the report or completely wrong. And despite the fact that the bearing supporting the rear of the compressor section failed and caused the compressor to misalign and stall(rather loudly, I might add!) there was no external indication of any damage whatsoever to the engine when we looked at it on post flight.
Whatever the case, the crew in this incident appear to be “Legends”, as the Aussies put it. Great job!
fltmech
I ask only because my myself and my crew once experienced an engine failure due to a ruptured combustion liner(on a T700-700) and by the time the final report was issued 6 months later everything we had in our incident statements was either left out of the report or completely wrong. And despite the fact that the bearing supporting the rear of the compressor section failed and caused the compressor to misalign and stall(rather loudly, I might add!) there was no external indication of any damage whatsoever to the engine when we looked at it on post flight.
Whatever the case, the crew in this incident appear to be “Legends”, as the Aussies put it. Great job!
fltmech
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In all the training I received, Oz and USA military and civil it was stressed running landings in single hydraulic 204/205, (dual hydraulic system not a problem because you have one remaining) don't attempt to hover, so never tried, I prefer to follow the manual and what I've been trained to do, realising of course if you're presented with a situation where you have to you do your best, if you bend things then in the doing because you were unable to comply with the manual or training you can hardly be hung out to dry, only 3100 hours in the single hydraulic 204/205. If hovering hydraulics out is so easy why then the emergency procedure as written, even the humble 206 recommends a run on? Test pilot I ain't, I like to follow the manual.
From the Huey manual, bolding at 5 mine.
9-37. Hydraulic Power Failure. Hydraulic power failure will be evident when the force required for control movement increases; a moderate feedback m the controls when moved is felt, and/or the HYD PRESSURE caution light illuminates. Control movements will result m normal helicopter response. In the event of hydraulic power failure:
1. Airspeed - Adjust as necessary to attain the most comfortable level of control movements.
2. HYD CONT circuit breaker - Out. If hydraulic power is not restored:
3. HYD CONT circuit breaker - In.
4. HYD CONT switch - OFF.
5. Land as soon as practicable at an area that will permit a run-on landing with power. Maintain airspeed at or above effective transitional lift until touchdown.
From the Huey manual, bolding at 5 mine.
9-37. Hydraulic Power Failure. Hydraulic power failure will be evident when the force required for control movement increases; a moderate feedback m the controls when moved is felt, and/or the HYD PRESSURE caution light illuminates. Control movements will result m normal helicopter response. In the event of hydraulic power failure:
1. Airspeed - Adjust as necessary to attain the most comfortable level of control movements.
2. HYD CONT circuit breaker - Out. If hydraulic power is not restored:
3. HYD CONT circuit breaker - In.
4. HYD CONT switch - OFF.
5. Land as soon as practicable at an area that will permit a run-on landing with power. Maintain airspeed at or above effective transitional lift until touchdown.
Megan,
One does not have to be a Test Pilot to learn the handling qualities of an aircraft.....training plays a role in that as I recall.
Lawyers and Fort Rucker Flight Standards Mafia had more to do with that than did reality.
Remember the Army was big on standardization and thus had to write procedures based upon the lowest common denominator as does any large organization in its procedures manuals.
Short answer....doing a run on landing on a suitable surface at just above ETL using a shallow approach works for the minimum standard Pilot which is what the Army with thousands of aircraft and many thousands of minimum standard pilots flying the machines had to plan for.
I concur with Albatross that despite what was in the Huey Manual is not because of any great difficulty in the handling of the any of the Huey family less the C and M models which had the 540 Rotor system.
Same for the 206...same technique worked fine in it.
The "trick" was to not try to move the cyclic but rather just apply some pressure on it in the direction you wanted it to move and let the normal feedback actually move the cyclic for you.
Of course there is always the question of what do you do if there is not a place suitable for a 20 knot touchdown running landing....if the Flight Manual does not spell it out for you and you had not practiced it beforehand at some time in the past.
Running landings into muddy rice paddies would have been fairly interesting I would imagine.....or skiing across a heli-deck offshore.
My preference was to retain a slight bit of forward movement across the ground but only enough to assist in keeping the skids straight at touchdown and avoid hovering if possible.
One does not have to be a Test Pilot to learn the handling qualities of an aircraft.....training plays a role in that as I recall.
Lawyers and Fort Rucker Flight Standards Mafia had more to do with that than did reality.
Remember the Army was big on standardization and thus had to write procedures based upon the lowest common denominator as does any large organization in its procedures manuals.
Short answer....doing a run on landing on a suitable surface at just above ETL using a shallow approach works for the minimum standard Pilot which is what the Army with thousands of aircraft and many thousands of minimum standard pilots flying the machines had to plan for.
I concur with Albatross that despite what was in the Huey Manual is not because of any great difficulty in the handling of the any of the Huey family less the C and M models which had the 540 Rotor system.
Same for the 206...same technique worked fine in it.
The "trick" was to not try to move the cyclic but rather just apply some pressure on it in the direction you wanted it to move and let the normal feedback actually move the cyclic for you.
Of course there is always the question of what do you do if there is not a place suitable for a 20 knot touchdown running landing....if the Flight Manual does not spell it out for you and you had not practiced it beforehand at some time in the past.
Running landings into muddy rice paddies would have been fairly interesting I would imagine.....or skiing across a heli-deck offshore.
My preference was to retain a slight bit of forward movement across the ground but only enough to assist in keeping the skids straight at touchdown and avoid hovering if possible.
[QUOTE][The "trick" was to not try to move the cyclic but rather just apply some pressure on it in the direction you wanted it to move and let the normal feedback actually move the cyclic for you/QUOTE]Pity no one ever mentioned the "trick" rather than hammering home the don't try to hover message, of course wind will help in a hover case. In all my time only ever had one acquaintance lose hydraulics, non combat Huey Vietnam.
One occasion on a Huey....in Army flight school during the final phase of training....and two newbie Pilots out doing a Route Recon Mission.
What we experienced was the Collective was very light up...and really hard to move down to the point we did not give much thought to the cyclic forces as the collective was where our focus was.
It required so much force that I had to really cinch down my seatbelt or it would cause me to raise out of the seat.
We returned to Tac-X the Field Training Site and landed to the side of the field set aside for the maintenance operation.
On a 206 I had a collective jam that was at a power setting that would not allow me to land as it was at a power setting a bit above that for hover.
Did a go around and on the second approach used the Throttle to reduce the power sufficiently to make landing possible and did to the parking spot which was in an open area.
What we experienced was the Collective was very light up...and really hard to move down to the point we did not give much thought to the cyclic forces as the collective was where our focus was.
It required so much force that I had to really cinch down my seatbelt or it would cause me to raise out of the seat.
We returned to Tac-X the Field Training Site and landed to the side of the field set aside for the maintenance operation.
On a 206 I had a collective jam that was at a power setting that would not allow me to land as it was at a power setting a bit above that for hover.
Did a go around and on the second approach used the Throttle to reduce the power sufficiently to make landing possible and did to the parking spot which was in an open area.
One occasion on a Huey....in Army flight school during the final phase of training....and two newbie Pilots out doing a Route Recon Mission.
What we experienced was the Collective was very light up...and really hard to move down to the point we did not give much thought to the cyclic forces as the collective was where our focus was.
It required so much force that I had to really cinch down my seatbelt or it would cause me to raise out of the seat.
We returned to Tac-X the Field Training Site and landed to the side of the field set aside for the maintenance operation.
On a 206 I had a collective jam that was at a power setting that would not allow me to land as it was at a power setting a bit above that for hover.
Did a go around and on the second approach used the Throttle to reduce the power sufficiently to make landing possible and did to the parking spot which was in an open area.
What we experienced was the Collective was very light up...and really hard to move down to the point we did not give much thought to the cyclic forces as the collective was where our focus was.
It required so much force that I had to really cinch down my seatbelt or it would cause me to raise out of the seat.
We returned to Tac-X the Field Training Site and landed to the side of the field set aside for the maintenance operation.
On a 206 I had a collective jam that was at a power setting that would not allow me to land as it was at a power setting a bit above that for hover.
Did a go around and on the second approach used the Throttle to reduce the power sufficiently to make landing possible and did to the parking spot which was in an open area.
Not super familiar with NH-90, is an uncontained engine failure very common for the RTM-322 engine used in this aircraft or has there been some embellishment as the story is told/retold by some that don’t know the real story? It seems this failure mode on modern turbine engines is becoming pretty rare.
Usually needs Engine vent procedure before another engine start to spread the temperatures.
If not done, it could lead to engine stagnation during engine start due to the compressor blades rubbing the housing. In the extreme case, later brake down in flight due to the damage.
There is at least one or two cases known of this happening.
Uncontained, as in releasing engine parts via the exhaust, yes thats probable.
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The inboard strap fittings have adjusters for the "neutral point" of the TT strap twist. If not adjusted with flight test then life can be a little more interesting!
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In all the training I received, Oz and USA military and civil it was stressed running landings in single hydraulic 204/205, (dual hydraulic system not a problem because you have one remaining) don't attempt to hover, so never tried, I prefer to follow the manual and what I've been trained to do, realising of course if you're presented with a situation where you have to you do your best, if you bend things then in the doing because you were unable to comply with the manual or training you can hardly be hung out to dry, only 3100 hours in the single hydraulic 204/205. If hovering hydraulics out is so easy why then the emergency procedure as written, even the humble 206 recommends a run on? Test pilot I ain't, I like to follow the manual.
From the Huey manual, bolding at 5 mine.
9-37. Hydraulic Power Failure. Hydraulic power failure will be evident when the force required for control movement increases; a moderate feedback m the controls when moved is felt, and/or the HYD PRESSURE caution light illuminates. Control movements will result m normal helicopter response. In the event of hydraulic power failure:
1. Airspeed - Adjust as necessary to attain the most comfortable level of control movements.
2. HYD CONT circuit breaker - Out. If hydraulic power is not restored:
3. HYD CONT circuit breaker - In.
4. HYD CONT switch - OFF.
5. Land as soon as practicable at an area that will permit a run-on landing with power. Maintain airspeed at or above effective transitional lift until touchdown.
From the Huey manual, bolding at 5 mine.
9-37. Hydraulic Power Failure. Hydraulic power failure will be evident when the force required for control movement increases; a moderate feedback m the controls when moved is felt, and/or the HYD PRESSURE caution light illuminates. Control movements will result m normal helicopter response. In the event of hydraulic power failure:
1. Airspeed - Adjust as necessary to attain the most comfortable level of control movements.
2. HYD CONT circuit breaker - Out. If hydraulic power is not restored:
3. HYD CONT circuit breaker - In.
4. HYD CONT switch - OFF.
5. Land as soon as practicable at an area that will permit a run-on landing with power. Maintain airspeed at or above effective transitional lift until touchdown.
One pilot for another company experienced a failure that had the hydraulics rapidly going on-off-on continuously …it was caused by contamination of the fluid which caused actuator problems..He stated it was very interesting until he got the system off. Of course it all happened during bad weather in a steep turn at low level as he was doing a recon of a confined area. (The aviation Gawds were just bored and needed a good laugh he guessed).
I experienced one actual in a 206 (total loss of hyd fluid) and 3 in AS350D ASTARS…2 belt failures and a pump failure. All ended in a no hover, zero speed landing on a small pad. Flying an Astar with no hydraulics for 20-30 minutes was good right hand / arm exercise. ( rule #1 turn off that ***** Car horn so you could think!) .
I had a # 2 pump failure in a 412 once too but that was just a “Land ASAPossible event”.
Never had an actual in a 204/205A or A-1 or 212. However, in our company training you were expected to land zero speed. We did, however, practice the slow speed run on too.
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The article seems to infer that since “hot starts” were supposedly the cause of an accident in 2010, that must be the case again. And even though the investigation of THAT accident revealed a software issue and Airbus provided a fix for this issue, 13 years ago, the Australian Army somehow left this one aircraft not updated for, 13 years.
Sure, I’m sure that’s what happened. 🙄 I find this pretty unlikely unless there is some supreme level of truth ineptitude in the AUS Army. Curious what others think.
FltMech
Sure, I’m sure that’s what happened. 🙄 I find this pretty unlikely unless there is some supreme level of truth ineptitude in the AUS Army. Curious what others think.
FltMech
The RTM322 is sensitive to spool bending after a time intervall of shut down.
Usually needs Engine vent procedure before another engine start to spread the temperatures.
If not done, it could lead to engine stagnation during engine start due to the compressor blades rubbing the housing. In the extreme case, later brake down in flight due to the damage.
There is at least one or two cases known of this happening.
Uncontained, as in releasing engine parts via the exhaust, yes thats probable.
Usually needs Engine vent procedure before another engine start to spread the temperatures.
If not done, it could lead to engine stagnation during engine start due to the compressor blades rubbing the housing. In the extreme case, later brake down in flight due to the damage.
There is at least one or two cases known of this happening.
Uncontained, as in releasing engine parts via the exhaust, yes thats probable.
Airbus says customers fault. Software not updated.
https://asiapacificdefencereporter.c...date-software/
https://asiapacificdefencereporter.c...date-software/
If the enginge was shut down for >10 minutes but less than 3hrs a vent prodecure should be performed before the engine start.
If the vent procedure is not performed when needed, the bent engine shaft could cause rubbing between compressor blades and the housing, causing damage.
There is at least a few examples of this since before, causing the engine to seize. Without mention a specific nation, it has happened that the engine vent procedure was “forgotten” or something like that, causing engine failure in the flight that followed that engine start with no vent.
The software change was implemented in my Air force, progressively combined with retrofit to FOC.
After booting the helicopter a software function decided if engine vent is needed, if so a “HOT” flag is shown at the engine/or engines that need to be ventilated.
The software reminds the pilot that engine vent is needed (theres also a semi automatic built in help), and also shortens the 3h window for when it is actually needed.
Regardless of this any engine start need to be carefully looked for stagnation in the N1 below 50%, and there time limits for having the N1 not increasing as it should.
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Things can get missed in any system I suppose, even with a message to warn you a task needs to be done, pretty bad that missing this step could cause your engine to fail though.
FltMech
Last edited by Senior Pilot; 18th Apr 2023 at 11:31. Reason: Fix quote
If the vent procedure is not performed when needed, the bent engine shaft could cause rubbing between compressor blades and the housing, causing damage
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The output shaft is the inner shaft and the shaft connecting the compressor and turbine is therefore hollow, making it possible to get one side of the shaft hot and the other cold = bent by different temperatures.
Shaft bow - When a gas turbine engine is shut down it will develop a circumferential thermal gradient vertically across the compressor due to hot air rising from the cooling metal components and pooling at the top. As the hot compressor rotor drum and casing cool and contract in the presence of this thermal gradient, they do so non-uniformly and therefore will bend slightly.
Article here on the subject.
https://www.researchgate.net/publica..._Initial_Study
Article here on the subject.
https://www.researchgate.net/publica..._Initial_Study
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