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Chinook - Still Hitting Back 3 (Merged)

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Chinook - Still Hitting Back 3 (Merged)

Old 12th Sep 2010, 13:06
  #6781 (permalink)  
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Safety Criticality

May I tap memories please.

We know that, by MoD's policy directive of the time, the FADEC software was Safety Critical; because no manual reversion was possible. The policy was issued by DUS(DP) on 14.12.89 and reiterated on 2.6.92. It was a joint policy, agreed by Industry.

Both Boeing and Boscombe agreed, but MoD denied it. (A common theme, in denial about their own mandated policies).

Question - Did MoD ever admit it was Safety Critical?
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Old 12th Sep 2010, 17:43
  #6782 (permalink)  
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Surely this would be a matter of record in an DHP archive?
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Old 12th Sep 2010, 19:26
  #6783 (permalink)  
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Much of these records were destroyed in the move to AbbeyWood (1996). It was announced in 1995 ABW would be a paper-free environment, and there would be space for less than 10% of the necessary filing cabinets. Therefore, archive or ditch. The MoD archives (at Kew I think) couldn't cope.

I recall on our first day at ABW the security jobsworth asked to see our Classified Documents Register. He then asked to inspect the documents (often large books and manuals) in their secure place. He was pointed to a huge pile that had been dumped on the floor in the middle of the floorplate. And that was just the TS and S stuff!!
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Old 12th Sep 2010, 21:12
  #6784 (permalink)  
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You just couldn't make this stuff up, could you? How ironic that some of the most professional people as well as being the most bloody courageous that this country can boast of, its Armed Forces, are administered and directed with such Gross Incompetence. I mean, if you made a movie or wrote a book with all this included it would be derided as too far fetched and bordering on fantasy. Would that it were so but tragically it's only too true, only to real, and very very deadly! God's teeth, how long do we have to wait, Oh Lord, to rid ourselves of this monstrous carbuncle that is Her Majesty's Ministry of Defence?
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Old 13th Sep 2010, 17:36
  #6785 (permalink)  
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Thanks T - just thought I'd draw that out for public consumption!

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Old 13th Sep 2010, 19:09
  #6786 (permalink)  
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dalek , your 6738,6775,6796
The report shows the TANS to be working to a very high spec approaching the Mull. Seven satellites in solution and a doppler within 330 m of the GPS position. Overall accuracy would have been around 10 m, maybe even better
..... the overall accuracy of the Stans was nothing like as good as you surmise , the Racal report only tells half of the story........
Although the GPS and Doppler positions were 330m apart from each other , they were both wrong from the true location ....
The GPS position was 193 metres away from the real/true lat/long on a heading of 235 Degrees True......
The Doppler was 173 metres away from real/true on heading 102 Deg. T....
..(so when navigating on GPS , everything is moved up the hillside 193 metres in the direction 055 degrees.).

A Chinook contributor I have recently pm'd thinks Holbrooks initial estimate of speed was wrong but one of 120 - 130 IAS was more likely. This ties in with the RACAL estimate of 127.5 TAS 151 GS at impact. So just where was negligence at this point?

..not really an estimate I think , the Doppler and GPS groundspeeds were calculated directly...and were in close agreement , and although some values referred to in the Racal report are instantaneous ones , a sort of snapshot at the time.......the ground speed is a two minute rolling average , which covers the period of waypoint change and the earlier point of closest encounter with the yacht.....so the 151 knots groundspeed is probably correct .......and fits well with performing a high speed transit across open water , slowing as the coast was approached ...
So what I can easily understand is how RACAL could extract data at powerdown. What remains a mystery to me is how they could possibly interpret where the rotary switches were, and what buttons were pressed just leading up to the accident?
..in any modern equipment which computer based , various values are stored in memory locations , and may be used by different routines .( Only data which might be needed again is worth saving , so altitude for example is not saved regularly as it was only really intended to help the GPS receiver if it is struggling with too few satelites )
....the panel controls can be 'remote' ie... a separate circuit board with a cable to connect it to the main board....and again the control positions can be scanned and saved in memory locations........most car radios work this way today , thats why the volume control can go round and round ......it is no longer a logarithmic potentiometer , but a pair of sensors on a slotted disc which only has to tell the logic which way to step the volume ........
...there probably was a record of the last 50 or 100 keystrokes , but it was not felt pertinent to publish the information in the public domain....

rgds Robin...
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Old 15th Sep 2010, 07:40
  #6787 (permalink)  
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I think your 6849 post is the best I have read on this subject.

Thank you for clarifying many points that were beyond my simple old aircrew brain.
If the last 50 to 100 keystrokes could be extracted, it would be possible to establish exactly where, when and how the crew changed Waypoints. There are a couple of problems with this.
1. By RACALS own admission this equipment was not designed to retrieve Historic Data. In any reasonable Court or Tribunal, this is inadmissable evidence.
2. This Data was not pubished, so has any expert from the Mull Group ever been able to examine this evidence?
3. When was the display switched off? Why was this very important event never nentioned in the Analysis?

You say that the 151 G/S was not the instantaneous value, but the system average of the final 2 minutes of flight. It makes sense.
Mr Cable gives the G/S at impact of 174.
If both RACAL and Cable are correct then there was a fairly dramatic acceleration in the final phase of the flight.
Since no sane aircrew accelerate into deteriorating weather conditions, the only conclusion is engine runaway??
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Old 15th Sep 2010, 12:10
  #6788 (permalink)  
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You raise a very interesting comment on aircraft speeds. As it happens in the last day or so I have been "delving" into a BD report PE/CHINOOK/41 dated 22 October 1993, which was jointly signed by the then Superintendents of Flying and of Aircraft Dynamics, and which is one of several additional reports called up as being an essential element of the Interim CA Release Recommendations. As far as I know none of these reports were assessed by the BoI.

Paragraph 21 of this report says:

Flight Envelopes The aircraft's handling characteristics were assessed briefly throughout the flight envelope up to 5000ft at AUMs up to 19000 kg. As with the Mk 1 aircraft, the maximum speed and manoeuvring capability were limited by the need to keep the Cruise Guide Indicator (CGI) in the Green segment, with only transient excursions into the Yellow band during turns. The aircraft handling characteristics were essentially unchanged from the Mk 1. As speed was increased the vibration characteristics of the aircraft increased significantly. The A&AEE Vibration Assessment Rating Scale was used to assess cockpit vaibration levels. At approximately 130 kn IAS, the vibration became more noticeable at VAR 5 (Moderate - Experienced aircrew are aware of the vibration but it does not affect their work at least over a short period.) and as the speed was increased to maximum possible with the CGI on the edge of the Green band, 150 kn IAS, the vibration was rated as VAR 7 (Severe - Vibration is immediately apparent to experienced aircrew even when fully occupied. Performance of primary task affected or tasks can only be done with difficulty.) During all the tests conducted the maximum flight envelope speeds were not reached as the CGI approached the Yellow band, with transient excursions into this band, before reaching Vmax. The vibration characteristics were similar to the Mk 1 and were unsatisfactory.

Assuming that ZD 576 exhibited similar vibration characteristics to the BD trials aircraft it seems to me as a "simple" engineer that the crew were very unlikely to have deliberately flown at some of the claimed speeds - especially given the VIPs in the back, but I will happily "bow" to more expert opinion.


Last edited by John Blakeley; 15th Sep 2010 at 12:14. Reason: Typo
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Old 15th Sep 2010, 16:12
  #6789 (permalink)  
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Dalek, the acceleration could have a number of causes. I am a staunch supporter of the cause here, however to pre-empt the doubters on forum, sadly, they could have shoved the nose forward to get down out of cloud. The weather was awful that day when we lifted from Aldergrove.
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Old 15th Sep 2010, 19:47
  #6790 (permalink)  
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I am disappointed in what you have written about vibration levels at speed - the Mk2 was appreciably better and indeed it was said that ZD576 had been at speeds of over 140 kts airspeed earlier on that fateful day and it had been fine.
You all seem to be forgetting that the windspeed increased significantly over the landmass and that analysis does not have the airspeed having to have been excessive for the (high) ground speed to have been realised.
All that is known about speed, track, engine state, a/c attitude, etc is consistent with them having been surprised at their immediate proximity to the ground and the a/c very much flew straight in apart from the apparent attempt to initiate a "quick stop" in the last seconds.
I have suggested a scenario which may account for them confidently approaching as they did but apparently that the equipment concerned is still considered rather “OPSEC” is enough for you all to put your blinkers on.
There is nothing greater in terms of national security than getting to the bottom of what happened that day if it is at all possible to do so – we have not exhausted all opportunity of getting to the truth if we ignore the possibility of the use of this equipment.
If you have any input but are (quite understandably) concerned about breaking security regulations or jeopardising your career, why not explore some way of getting your input directly into the inquiry confidentially – there must be a way.
You do not have to subscribe to any “conspiracy theory” but those running the inquiry need to have available a whole picture of the systems available to the pilots and their practical use – as this has thus far not been volunteered by the establishment (MOD/RAF), it can only come from individual aircrew who have a different kind of courage.
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Old 15th Sep 2010, 22:19
  #6791 (permalink)  
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I'm sure you're a love and all that but there are several people here much smarter than me and probably you that have, shall we say, relegated your theory to the realms of "unlikely".

While I can understand your desire to be proven right, can you not sit back, (happy in the knowledge that you have eloquently put forward your case), and wait for the eventual outcome? Because, right now, you are becoming nothing more than the "white noise of the internet" in a thread that has more important overall implications than someone trying to hide some equipment.

I have a particular interest in the eventual outcome because I am probably still the only RAF aircrew to refuse to operate the Chinook, (albeit the MkI), on the basis that it was, indeed, un-airworthy.
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Old 16th Sep 2010, 06:10
  #6792 (permalink)  
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I accept most of what you say. I was just showing that one of the Sqn Ldr Burke theories did fit the available facts. I am sure there are other theories that do also.
Look again at the RACAL / Cable figures. To make them both correct, there had to be a a 25 to 30 increase in IAS in the very late stages of flight.
Starting at 120 - 125 IAS, 250 ft MSD and just pushing the stick forward, how much speed do you think you could gain before impact? Not a lot.
If RACAL and Cable are both correct, some of the speed increase must come from increased power, deliberate or otherwise.
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Old 16th Sep 2010, 10:23
  #6793 (permalink)  
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No probs Dalek, I actually agree with the increased power theory, however if you state something happened on this thread you will be taken to task by others. Truth is, none of us knows what ACTUALLY happened.....
I was flying out of Aldergrove with Jaffa D many years ago and we had a Puma engine run up to full power whilst in terrible terrible weather conditions. The only option is to initially pull max to contain Nr and then diagnose and deal with it. For a while we were at 145kts/100'/ cack visibility/ low cloud and it was icing conditions above. Not where you want to be.....
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Old 16th Sep 2010, 16:54
  #6794 (permalink)  
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John Blakeley

I was interested to read the article about vibration and thought this might be relevant.

From my time on the civilian Chinook, vibration levels were enormously effected by weight. At MAUW as takeoffs from ABZ invariably were, despite what the graphs said, 115 knots gave a comfortable vibration level whereas 120 knots was uncomfortable and brought complaint from the passengers.

On the return leg when most of the 14,000 lbs of fuel had been burnt, 135-140 knots (the civilian VNO) was usually quite comfortable.

On the flight in question with just over a half load of pax, even with return fuel, it seems unlikely that the aircraft would have been anywhere near MAUW in which case vibration was unlikely to have been a problem.

Perhaps an HC2 pilot could comment.
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Old 16th Sep 2010, 18:16
  #6795 (permalink)  
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<<... we had a Puma engine run up to full power whilst in terrible terrible weather conditions. The only option is to initially pull max to contain Nr ... >>
I made this point a long time ago that one could discount an engine runaway on this consideration alone - it would have been the hand of God which would have saved them in their circumstances.
So cut that out of the possibilities, eh?
Still zilch on the nav systems - says a lot.
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Old 17th Sep 2010, 06:44
  #6796 (permalink)  
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As a regular contributor of this thread I know who all the doubters are. The regular ones are John Purdey and Cazatou. I have never known them be drawn in on a subject they will certainly lose. I bet the farm they will not bite on this one. Here goes.

1. We know (fact) the average G/S for the sortie was 155 (D/T).

2. From forecast and some actual W/V's, the average IAS was 135 - 140.

3. The aircraft approached the Mull Wpt at less than IAS 127. (RACAL)

4. The aircraft was in VMC. (Holbrook)

5. Take 3 & 4 together then the Wratten contention that the crew were flying "to fast for the conditions at Waypoint change", is plain wrong. The crew must have slowed approaching the Mull, showing sound Airmanship.

6. At some stage, very late in the flight there was a 25 - 30 kt speed increase. (Cable). This increase must have come very late, or the Average speed would have been higher.

7. Some of this increase must have come from increased power.*
* Not backed by firm evidence, just strong circumstantial.

For the above list to be wrong, there has to be a major problem with either the RACAL analysis or the Cable evidence.

Mr Cable is an experienced Accident Investigator dealing with real wreckage.

The RACAL analysis came from measuring wiggly amps from a crash damaged,non certified TANS.

So which evidence is likely to be wrong? The problem for the MOD apologists is the Wratten, Day evidence is based largely on the RACAL analysis. If this is discounted, their evidence goes from speculation to worthless.

So come on JP, Caz and the very self important Atlantic Cowboy (if you are still around). Shoot me down.

Another one for you Caz. In our earlier jousts, you questioned my helicopter experience. You also said that the faults described by Sqn Ldr Burke were so isolated that they could not possibly have happened at the Mull accident.
Jayteeto has just described a serious incident that happened to him. Very similar to one envisaged by Sqn Ldr Burke.

He probably survived by a combination of skill, luck and location. Miss out on one and you arer screwed.
Still say that Burke could not have happened to our crew?

Last edited by dalek; 17th Sep 2010 at 07:04.
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Old 17th Sep 2010, 06:44
  #6797 (permalink)  
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So cut that out of the possibilities, eh?
Nope, you daft hay'p'th!
Because we just cannot know for sure...hence doubt - bucketfuls of it!
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Old 17th Sep 2010, 08:22
  #6798 (permalink)  
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Walter's Disappointment


Re your 6866. I am sorry my words disappointed you - they were not mine but the words of two of the Superintendents at Boscombe Down responsible for the Release to Service trials of the Chinook. I did not point them out in this thread because I thought they gave a cause for the accident (although some of the subsequent postings by people better qualified than me to comment raise some interesting points), since because unlike you or the Reviewing Officers I am not trying to speculate on a reason. Like everyone else, including you, I don't know - and that is the reason for this thread - to right the injustice of the Gross Negligence verdict based on speculation and not facts.

However, part of the "facts" which show just how unjust this verdict was, and which MOD's own "no new evidence" intransigence has continued to reinforce, was the flawed processes leading to the introduction to service of the Mk2. Thus what I was trying to do, obviously too obtusely, in my post was to show yet another area (ie the BD reports which were an essential part of the CA Interim Release Recommendations) missed by what in my view was a totally inadequate investigation by the BoI process, and to provide yet another "fact", albeit possibly minor, that forms part of the wider picture of doubt on the airworthiness of the aircaft at that time, and the poor judgement displayed by management at all levels (but not the pilots who wanted a Mk1 - so they did not seem to have an inkling of your "secret" mission either) in its use for this high profile sortie in terms of both the fleet clearances and the individual airworthiness and even servicability problems which were displayed by ZD 576.

If you would like another unmentioned "fact" from the BD reports on which I have not seen any comments from the BoI try this:

Transmission Debris Screens - A crewman must inspect the Transmission Debris Screen magnetic indicators on the Maintenance Panel at least every 5 minutes during flight unless other flight safety requirements take priority.

This wasn't just in BD Reports it is in the Interim RTS at AL1 which was extant at the time of the accident. I have never seen this requirement mentioned in the BoI (if I recall correctly the DECU connector check every 15 minutes (which was based, inter alia, on an incident on the trials aircraft), wasn't brought out either until Robert Burke mentioned it.) No, I am not suggesting that this was a potential cause of the accident - the AAIB did look in detail at this area and it appears to be clear - but would you put your wife and kids in an aircraft which required such checks? Were these checks even being carried out?

What, in my view, is clear from reading the plethora of detail in the BD Reports is that they should have formed part of any "proper" BoI investigations into such a high profile accident on a newly converted aircraft, and I still wonder why this was not the case - words which spring to my mind include "inadequate", "incompetent", "directed", "presumption" and a few others less fit to print! But I don't know which one might apply.

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Old 17th Sep 2010, 12:05
  #6799 (permalink)  
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Dalek & John Blakeley

Excellent posts.

Dalek, you said;

In our earlier jousts, you questioned my helicopter experience. You also said that the faults described by Sqn Ldr Burke were so isolated that they could not possibly have happened at the Mull accident.

Sqn Ldr Burke offered the following evidence;
“UFCMs were relatively common at the time of the accident and were occurring for years afterwards, and if caused by the Automatic Flight Control System (AFCS) leave no trace and are completely random in nature. From the first, a UFCM has been a primary possible cause of this accident and if it occurred in roll or yaw could well explain some of the still unexplained aspects of the crash. (It) would leave no clues in the wreckage”. (RB - 14th September 2002).
On 28th February 1994, 3 months before the accident, the RAF issued Special Flying Instruction (SFI) – SFI (RAF) Chinook 12. This warned;
“SFI(RAF) 12, Issue 1 (Restrictive) – Chinook HC Mk2. Undemanded Flight Control Movement.
There have been a number of incidents of yaw kicks on Chinook HC Mk2 ZA718 during recent flight trials at Boscombe Down. The characteristic is manifested by very sharp uncommanded inputs to the yaw axis which result in a rapid 3-4 degree change in aircraft heading, in both the hover and when in forward flight when the aircraft is subject to high levels of vibration.
Any aircraft exhibiting these characteristics is to be treated as having an Undemanded Flight Control Movement (UFCM). The heading hold is to be disengaged and the aircraft is to be landed as soon as practicable.
Engineering modification action is in hand to cure the cause of the problem and this SFI will be cancelled once the modifications (have) been carried out.
Action addressees acknowledge receipt of this SFI to RAF Handling Squadron”
Sqn Ldr Burke has kindly given me permission to quote him, thus;
“No. I did not know of this SFI. I suspect that very few people, either aircrew or groundcrew did. When another pilot (by coincidence Witness A) had this problem quite severely in Northern Ireland and I was called over there to fly the aircraft sometime after the Mull accident, we were not aware (of the SFI). Often SFIs took a long time to reach the actual front line operators, getting bogged down in the various layers of admin & command”.
I find this utterly compelling. Sqn Ldr Burke has been both ridiculed by MoD and prevented from giving crucial evidence, yet it transpires MoD knew he was right all along.

You will note “Engineering action is in hand” and “modifications” (plural). As everyone probably knows, such modifications don’t happen overnight. There must have been UFCMs, reports, contracts placed to investigate, engineering solutions agreed and modifications schemed to result in such a firm statement. This also begs the question why no immediate notification took place when the UFCMs first commenced.

Finally, try as I may I cannot find any reference to this SFI in any BoI or other inquiry papers.

I sincerely hope the new Review takes a look at this evidence.
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Old 17th Sep 2010, 17:35
  #6800 (permalink)  
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Crikey tuc, that stuff seems pretty damning of just the flight safety system, never mind this accident!
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