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Jammed Controls - Instances?

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Jammed Controls - Instances?

Old 14th Jun 2020, 22:21
  #21 (permalink)  
hum
 
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Here is the report on that incident in Ireland.


http://www.aaiu.ie/sites/default/fil...2001_007-0.PDF

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Old 14th Jun 2020, 22:42
  #22 (permalink)  
 
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Heard of a similar one to that described by wrench1 involving a Bo105 on Northern Lighthouse Board duties over Scotland. Happened at several thou feet in transit - pilot (ex-SAR SeaQueen driver) had absolutely no control for several seconds. There was also a Royal Oman Police 214ST incident concerning the collective, which was effectively disconnected with the aircraft in either level or gently-descending flight. Fortunately, both occurrences led to safe arrivals - wish I knew more about each of them.
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Old 14th Jun 2020, 23:00
  #23 (permalink)  
 
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Thud and Blunderís reference to a collective disconnect on an Omani 214ST reminds me of the 1986 North Sea ditching on that type that we had due to that reason. Same airframe as the cyclic problem described earlier.
https://www.gov.uk/aaib-reports/9-19...fn-15-may-1986
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Old 14th Jun 2020, 23:33
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On 4th August 1999 at Barrow Island, VH-BHM, an S76A operated by Bristow Helicopters, had a jammed cyclic in flight which resulted in an interesting 80kt landing.
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Old 15th Jun 2020, 02:13
  #25 (permalink)  
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Thanks to everyone that has posted.
That makes for some very interesting reading.

Evil Twin - how did you go about recovering the full open throttle?
Not one that I've spent much time thinking about before in the H269.
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Old 15th Jun 2020, 02:24
  #26 (permalink)  
 
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Originally Posted by JimEli View Post
There is a textbook method. In fact, its fully explained and located in the emergency procedure section of the RFM. It should have been covered in training. I believe any professional pilot would have at least studied it and they certainly would refer to it when necessary. May your good fortune always hold.
Have you read it for the Astar? It is useless and will not work, I have attached a copy, (albeit an old copy).
Attached Files
File Type: pdf
AS350 TR Failure.pdf (76.1 KB, 34 views)
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Old 15th Jun 2020, 05:59
  #27 (permalink)  
 
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Mick, I made several attempts at a run on after trying all sorts to trouble shoot (had the engineer on board) all aborted due to too much speed. On the final attempt the engine gave up at about 50í in the go around. We went end over end twice. I spent all of my spare nine lives and walked away without a scratch. Shook me up though and spent a long time with the general manager afterward working out what to do if it happened again.

The reason I was aiming at run-ons was it was revving so high I was concerned it would start throwing bits off before we had the chance to shut it down. Iím a bit older and wiser now and would have done as AC suggested and accept what ever overspeed occurred. That or if I had the chance get to alt and auto in were it to happen again

interestingly it happened again to the other heli school a few months later. That pilot after getting a lot of help from the ground got it up to sufficient altitude and pulled the mixture with a successful auto.

Iíve been carefully conserving my remaining life and anticipating trouble ever since.

Last edited by Evil Twin; 15th Jun 2020 at 06:10.
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Old 15th Jun 2020, 06:34
  #28 (permalink)  
 
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Some years ago ferrying an R44 with 2 pax from a smaller airfield to a bigger one about 20 minutes away. The 2 pax had come along to look at trial flights and possible training, and were invited along on the ferry flight.

Despite a proper brief, just after I lifted and moved a few feet forwards the collective felt "odd". One of those "that's not right?" moments, so straight back on the ground it was. On looking at the pax seatbelt it was routed over the top of the collective, not under, hence the restriction - I looked much more carefully at seatbelts after that.
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Old 15th Jun 2020, 08:59
  #29 (permalink)  
 
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(Never a helicopter pilot).

Can helicopters do a full and free check of flight controls with engine(s) running before lifting off? Or is it not possible to do that on the ground with everything turning, without damaging the rotors or the aircraft, or taking off? Genuine question.
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Old 15th Jun 2020, 09:40
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Normally, but depends on type, a full and free movement check is done before engine start. Once everything is turning and burning with the hydraulics fired up then rotor response is checked with a small movement of the cyclic. Anything more will tend to cause problems with fuselage lean, bashing the boom or damage to the droop stops.
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Old 15th Jun 2020, 09:55
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One from my memory banks.

Puma HC1 in the seventies. Start up, taxy off the ramp to the taxiway for take off. Engage autopilot and lift off into the hover. The aircraft pitches forward so I pull back the cyclic to level it. It pitches even more nose down and I have to pull in loads of collective to keep it clear of the ground. Just as we were about to charge into the scenery I tell myself the the cyclic control is reversed. I push forward on the cyclic and the aircraft responses by trying to zoom into space. There then follows a frantic ten or fifteen seconds where I learn to fly this thing with the for and aft control reversed. It is then in a reasonable hover and I place it back on the ground and shut it down.

The reason was finger trouble during an autopilot repair. The connections on a plug had been soldered incorrectly so the up signal was going to the down pin on the fore/aft servo and vice versa. After the engineers had spent several hours discussing the problem I was told, quite firmly, that I would avoided the panic if I had disconnected the autopilot.

I wish I had had the time to think of that.

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Old 15th Jun 2020, 10:07
  #32 (permalink)  
 
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Originally Posted by hum View Post
Here is the report on that incident in Ireland.


http://www.aaiu.ie/sites/default/fil...2001_007-0.PDF
Thanks... surprised they didnít have M&B issues with the size of that phone haha
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Old 15th Jun 2020, 10:14
  #33 (permalink)  
 
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"Does anyone have any first or second hand knowledge of a jammed control event"

About 5 years ago, I was working in a hangar and we received a report that one of our aircraft (AW139) which was on a test flight had a control problem and the pilot had issued a Pan call.
The aircraft carried out a run on landing on the airport runway and shut down immediately on landing.
The pilot reported that when flying, he was unable to move the cyclic aft to reduce speed, hence the need for the run on landing and I believe he shut the engines down as soon as the aircraft touched the ground (but I may be wrong on this).

The reason for the jam was due to one incorrectly positioned P-clip just aft of the mixing unit in the cabin roof.
An engine control cable cable had been replaced the previous day and when refitted, the P-clip in question was refitted 180 degrees out which resulted in the pitch rod running just below the P-clip rather than to the side of it.
Although a control check had been carried out both in the hangar and by the pilot on the preflight, no issue was found. However, once the cyclic was fully forward with the collective raised, the locknut on the end of the rod end was able to slip over the P-clip but due to the shape, it wouldn't slip over again when the cyclic was moved forward.

We were very lucky that it was a very experienced pilot at the controls.
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Old 15th Jun 2020, 10:51
  #34 (permalink)  
 
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Can helicopters do a full and free check of flight controls with engine(s) running before lifting off?
As Fareast says, the check is done before engine start. The controls are pretty stiff, with no hydraulics, and in some machines the controls won't move at all without hydraulics. Once the rotors are turning, a full pedal check would spin the aircraft on the ground and perhaps damage the tail boom attachments; full cyclic would hit the stops and perhaps chop off the tail; full collective sees you leap into the air.

Simple answer: no.
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Old 15th Jun 2020, 11:58
  #35 (permalink)  
 
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Originally Posted by Ascend Charlie View Post
As Fareast says, the check is done before engine start. The controls are pretty stiff, with no hydraulics, and in some machines the controls won't move at all without hydraulics. Once the rotors are turning, a full pedal check would spin the aircraft on the ground and perhaps damage the tail boom attachments; full cyclic would hit the stops and perhaps chop off the tail; full collective sees you leap into the air.

Simple answer: no.
Except for aircraft equipped with an electric hydraulic pump e.g AW 139.

Simple anwer maybe!!!

BO 105 suffered a control restriction when the hydraulic pack access door hold open rod became unlatched and the end fell into the bellcranks at deck level.
Gazelle suffered an full and immoveable jam in aft cyclic fortunately on the ground. Cause was mismanufactured friction discs at the base of the pilots cyclic.
Interestingly by it's nature this defect could be dormant. It occurred on a military Gazelle in the days when they didn't talk to anybody. So as no civil AD was ever issued
the fault could still be waiting to bite somebody.


Last edited by ericferret; 15th Jun 2020 at 12:10.
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Old 15th Jun 2020, 12:17
  #36 (permalink)  
 
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I remember an incident in the Middle East when I was behind a puma that was engaged n the ground idle process of shutting down, suffering a tail rotor pitch failure resulting in a full hardover to,I think, port, akin to full left pedal. Even though at ground idle and on the ground, the aircraft yawed violently. I can't remember the cause, maybe an actuator failure, but if that had happened in flight I cannot think of any remedy which would have resulted in a succesful outcome.
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Old 15th Jun 2020, 12:18
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I recall that Kaman lost an H-2 at the factory along with the crew of two test pilots and the cause was later determined to be nothing wrong with the machine, but that the copilots heel had become stuck in the floor opening for the cyclic on his side, thus jamming the control when the pilot moved the cyclic so as to trap the cyclic against the heel and against the opening edge. Perhaps the H-2 community can provide more detail-am I correct that it was some sort of speed run and they were both low and very fast?
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Old 15th Jun 2020, 12:18
  #38 (permalink)  
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Originally Posted by ericferret View Post
Except for aircraft equipped with an electric hydraulic pump e.g AW 139.

Simple anwer maybe!!!
Ascend Charlie was responding to a question regarding carrying out a check with the engines running:
The question was:
Can helicopters do a full and free check of flight controls with engine(s) running before lifting off?
so even on the 139 with its hydraulic pump, it's still not possible to do a F&F check of the controls with the engines running.
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Old 15th Jun 2020, 12:19
  #39 (permalink)  
 
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Two from me - both on Lynx and in NI.
Just after establishing in the near cruise near Omagh with a full load in the back and as a newish pilot, Captain asked if I would like to fly in balance. On attempting to put the ball in the middle, I found that the pedals were jammed and announced this to the Captain. Having found they were jammed on his side too. Having found that 40kts gave us fairly straight, we set ourselves up for a long slow approach to a sports field at the barracks. The point where we touched down was fairly firm but quite wet following recent rain which led to a 50 metere-ish run on. Feeling rather pleased with ourselves we called for tech assistance and waited for it to arrive. First to arrive though was the Garrison Quartermaster - who was also the Garrison Cricket Officer - and somewhat un-amused by the ploughed furrow across all 3 of his wickets. The cause of the jam was that, on the lynx, the left seat controls were removeable duals. The "Pip Pin" that secured one of the pedals had a retaining wire which had formed into a loop. The point in the loop where the 2 wires crossed had jammed between the stalk of the pedal and a bracket that held the "Brush strip" designed to keep FOD out of the control run.

Second one, about 5 years later, was doing some parachute drops over Ballykelly. On a run in at about 5000ft and 60kts when the pedals jammed solid. Tried all sorts to free them but nothing worked. Held the run in heading until over the DZ and got the jumpers away. Collective seemed a bit stiff but cyclic was okay. Found a "comfortable" speed and flew an approach back to the airfield. Suddenly, with about 100ft to go, everything freed off. Landed and shut down and awaited tech support. System tested by techs, no fault found, full hydraulic check - all serviceable. This check can be done on the Lynx as it has an Accessory drive system on the gear box that allows both hydrualics to be powered up without the blades turning - (in answer to Uplinkers post and Ascend Charlies reply). Hover check. all okay, short airtest, all okay, flew back to base. REME all over it through the night but nothing found. Next day, another crew due to take the aircraft when, during pre-flight "Full and free" control checks, everything locked up again. Aircraft returned to hangar where, deep in the control runs a small burr was noticed on the collective/yaw interlink which only affected it when the cyclic/collective interlink was in a certain position.
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Old 15th Jun 2020, 12:32
  #40 (permalink)  
 
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P2K4, either a run-on and careful shutdown ,or an eol....
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