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Chinook - Still Hitting Back 3 (Merged)

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Chinook - Still Hitting Back 3 (Merged)

Old 21st Jul 2010, 13:01
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dervish:
Sorry Chugalug if this has stepped on your toes
Not to my knowledge, dervish, but even if it were so feel free to trample all over me! What you say is very true and already well established on this thread. But that is caz's modus operandi; continually raise issues, totally ignore the answers, only to raise the same issues again later. In the meantime we are treated to another "farewell post" which in turn is followed by a post such as his above. I'm aware that I am guilty of playing the man and not the ball here, but these spoiling tactics that I describe do not advance anyone's case, pro or con, and reflect poorly on the supposed professional expertise that caz for one repeatedly claims. In short caz I am disappointed, very disappointed indeed!
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Old 21st Jul 2010, 13:45
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Chugalug 2

So you haven't read their testimony then?
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Old 21st Jul 2010, 13:48
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Originally Posted by cazatou
Chugalug 2

So you haven't read their testimony then?
Based on all the info available or just all the info presented Caz
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Old 21st Jul 2010, 14:18
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Chinook

Chug. It would be interesting to know what Mrrs Cable Parkinson and Smart think of your dismissal of their efforts. JP
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Old 21st Jul 2010, 14:55
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Thank you Chugalug




It would be interesting to know what Mrrs Cable Parkinson and Smart think of your dismissal of their efforts.

Do you, John Purdey, dismiss Mr Cable's assertion that the Tans was switched off at impact? If yes, then you are a hypocrite (sorry to be so blunt, but that is the correct word I think). If no, then you are accepting MoD's argument has no basis.
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Old 21st Jul 2010, 15:29
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Chinook

Dervish. Please stick to the point. JP
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Old 21st Jul 2010, 16:09
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AAIB Role

I had been trying to stay out of the circular arguments and the repeated mantra of Caz and JP, although I think SFFP got it right with his last comment - the AAIB investigation was very limited in terms of the information made available to the investigators as it was the BOI's responsibility, in which in my view they failed - partly for reasons beyond their control, fully to investigate the accident. The original AAIB report certainly did NOT give any grounds for a Gross Negligence verdict, and Mr Cable made this even clearer in his evidence to the House of Lords - to remind Caz and JP he said:

Evidence of Mr Cable, AAIB

98. As already mentioned, Mr Cable in evidence to us stressed that throughout the investigation the evidence was "remarkably thin" (QQ 956, 968, 1013). While the evidence available to him pointed strongly to the engines operating normally, i.e. without distress, at the point of initial impact, he conceded that this did not necessarily mean that this was in accordance with pilot commands (QQ 181-4). He further explained that the possibility of an intermittent fault prior to impact could not be dismissed (Q 182).

99. He further explained that the detachment of the pallet inserts and the components carried by them could possibly cause a restriction or jam. "It would be very difficult - impossible - to dismiss the possibility that there had been a restriction and evidence had not been found" (Q 196). This explanation is readily understandable given the crowded equipment in the broom cupboard. A balance spring is some 6 inches long by 1½ inches in diameter and its mounting bracket about 1½ inches long.

100. The only positive evidence of a fault possibly contributing to the accident was a radar altimeter system fault (AAIB statement para 7.2.17 and conclusions 48-9 and 52). However, in the light of all the evidence before us, we do not consider that this fault is likely to have been relevant.

101. Mr Cable summed the situation up thus:

"Where there is no fault found that does not mean that there was not a fault present. In this case I found it probable that on the engineering side as far as I could see there was not a fault highly relevant to the accident, but I certainly could not dismiss that possibility" (Q 264).

102. As already referred to in paragraph 58, the AAIB investigation disclosed a considerable quantity of very small metallic particles in residual hydraulic fluid in parts of the boost actuator for both the pitch integrated lower control actuator (ILCA) and the thrust lower control actuators (LCAs) together with the presence of four fine metal slivers up to 0.2 inches long on one of the servo valve screens of the yaw ILCA boost actuator. This contamination was thought to have been present prior to the accident (AAIB statement para 7.4.4).

103. In evidence Mr Cable expressed the opinion that a failure of both lower control actuator systems due to hydraulic contamination would be unlikely to be a major problem as it would merely reduce the boost on the pilot's control to the upper boost actuators which drive the rotor blades[29]. A jam of an upper boost actuator would be a very different matter (QQ 204-10).

104. The US Army, however, who operate very large numbers of Chinooks, take a different view. In a report of June 1997[30] on an incident when a Chinook turned upside down at about 1100 feet and righted itself at about 250 and where no exact cause could be established, hydraulic contamination was considered to be a possible cause. The recommendations section of the report[31] referred to "uncommanded oscillations, flight control movements, and flight attitude changes" possibly related to the performance of the upper boost actuators and metal contamination in part thereof.

105. The recommendations continued,

"An additional critical area is the integrated lower control actuators (ILCA). The metal contamination and moisture found in the pitch, roll and yaw ILCAs are considered critical to FLIGHT SAFETY. The amount of contamination found in the pitch and roll ILCA were considered sufficient to cause a disturbance in the normal operation of these components at any time. One solution may be to establish a drain point for each system 2 ILCA, since the corrosion and moisture contamination appears to be primarily found in system 2. CCAD shop personnel reported that some ILCAs arrive with secondary valves jammed due to internal corrosion. This means the unit is operating on the primary control valve with no back-up or secondary valve available. If the primary valve jams, in this situation, the capability to direct hydraulic fluid flow ceases.

The upper boost actuators and ILCAs deserve immediate and positive action, since these two areas are CRITICAL TO FLIGHT SAFETY, PERSONNEL SAFETY, AND EQUIPMENT SAFETY." [32]


Based on this evidence, and without in any way denigrating the work they carried out at the time "with the information made available to them", I suggest that use of the AAIB's much more extensive capabilties to look at the full causes of the accident was deliberately kept very limited, and even sticking just to their original report and their technical and forensic analysis of the wreckage they have been mis-quoted far too many times on this thread. Given what we now know the situation was it would be very interesting to have the AAIB carry out a FULL investigation of all the facts relating to the part played by the now well publicised deficiencies in the procedures for the introduction to service of the Chinook HC2, and the then airworthiness of the fleet and ZD576 in particular, in this accident. Perhaps the MOD will include them in their "promised" new investigation.

JB
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Old 21st Jul 2010, 16:17
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JP:
Chug. It would be interesting to know what Mrrs Cable Parkinson and Smart think of your dismissal of their efforts. JP
How many g's are there in disingenuous? No matter, the point (as you demand of dervish) is that far from being dismissive of the efforts of the AAIB, I wish that they had been the ones who conducted the Investigation originally. But of course they were not and were constrained to give advice on aspects of the accident as and when required by the Board, who of course were not trained accident investigators. If the AAIB had conducted this Accident Investigation they would have wanted to consider the checkered and troubled history of the HC2 as Released to Service. They would have wanted to know why this aircraft was Grossly Unairworthy along with its sister HC2's. They would have called as a crucial witness the RAF Odiham Test Pilot for evidence of repeated controllability faults in airframe and engines. They would have more fully quizzed the only eye witness called of the sea transit to Mull, and more urgently have sought others. They would in short have carried out a thorough and professional accident investigation. But as the man on the Nationwide ad said, "It doesn't work like that". "Dismissal of their efforts?" Not me sunshine!
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Old 21st Jul 2010, 16:18
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Dervish. Please stick to the point. JP
It was a simple question to a point YOU raised John Purdey. Do you dismiss Mr Cable's evidence or do you disagree with MoD?


If you are unable to answer my advice is to say nothing in the first place and stick to points you do understand.
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Old 21st Jul 2010, 18:27
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Chinook

As we have all too often seen in this thread, rational discussion quickly turns into unwarranted insinuation, invective and personal attack. Regards. JP
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Old 21st Jul 2010, 18:59
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John Purdey

Your posts are increasingly bizarre and irrational. Your refusal to answer simple questions is juvenile. This is a serious subject. Please grow up.
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Old 21st Jul 2010, 20:12
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JP:
rational discussion quickly turns into unwarranted insinuation, invective and personal attack
What rational discussion? You ask me a question about the AAIB Inspectors and I answer, though with no comment from you. Dervish asks you a question about the TANS switch and you don't answer. Let's make it a hat trick. Do you support the call for an independent accident investigation of this crash by the AAIB? Two questions for you JP. I doubt if you'll answer either:
As we have all too often seen in this thread
As to your complaints above, why don't you direct the Mods as to how to do their job again, as is your wont?
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Old 22nd Jul 2010, 05:49
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Chug/Dervish,
I fear you are wasting your time and effort with the likes of JP and Caz! They seem quite incapable or unwilling to consider any facts or suggestions that disagree with their own assessment of the case; they won't, therefore, answer your questions, I'm afraid. Their assessments may well be correct but, as there was no CVR/ADR, we will never know with 'absolutely no doubt whatsoever'.
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Old 22nd Jul 2010, 07:21
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Ask either of them to prove to you leaving absolutely no doubt whatsoever what actually happened that day and they will simply skate on by.

JP even previously acknowledged on here that he could state with any certainty what the pilots could actually see from the flight deck windows.

Continue if you guys will to try and get an answer from him but I doubt you ever will
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Old 22nd Jul 2010, 07:22
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Dervish
<<I think someone mentioned the toggle switch on the Tans that AAIB said was off, which is probably quite important as MoD's case is built on their assertion that the Tans and the rest of the nav was in perfect working order and displaying information correctly. >>
Now here's a thing that you could lose your lunch over – both of the above points were true!!!
The SuperTANS was working to the end (from the recovered data, thanks to the back up battery) and yet the switch was found in the OFF position – a switch designed so that it is difficult to accidentally turn off (you have to pull it out to turn it to the off position) and given the apparent dynamics of the impact it would have been just about impossible for it to have got like that through impact.
Mr Cable (AAIB) was adamant that it had to have been in the off position, the smoke deposits indicating that it must have been off before the ground fire spread enough to effect that area of the wreckage.
If it had not been for the back up battery, very little analysis from the navigation perspective would have been possible – and we would not have had the clue of the switch being turned off after the crash.
Feeling it in your stomach yet?
Someone right there thought he was being clever by switching off the nav computer but instead left us a priceless clue – pity about the battery back-up, eh?




That Turn
Some years back I brought it up on this thread that a right turn at or near the position where they had dropped route navigation (by changing the waypoint in the SuperTANS) tied in with the handling pilot having 035 on his HoSI course selector – this suggested that the turn was deliberate with something for the HoSI track bar to work off.
This should have been enough, I thought, to get pilots amongst you thinking.
Alas, so much later someone is able to come up with a post that questions the turn without any one of you correcting him – and just in case anyone genuinely interested is left confused, I am obliged to explain how the turn can be quantified.


With respect to distance/time calculations and the actual accuracy that the Doppler system had held, the manufacturers of the nav equipment, the Board of Inquiry, and the Boeing analyst (Mitchell) all accepted that the a/c had to have travelled straight and level with very little turning (from leaving the NI coast) – however, the Board assuming it went straight in with no turn at all and Boeing that it had a small turn to the right and assumed that this occurred at the position of waypoint change – I deduced that the turn occurred after when they changed the waypoint but sometime before they crossed the shoreline.


There are two sources of data indicating a turn in the vicinity of the point where the waypoint was changed in the SuperTANS:
the GPS showed a displacement off the previous track;
the Doppler (over the ground) showed a significantly changed track angle.


First the GPS:
we are fortunate that they changed the waypoint where they did as the position was therefore memorised (let's call this WPCHX) – we therefore have, within the one system and with reference to one coordinate system, a point close to the Mull, referenced to a waypoint that the same system had used to get them there (waypoint A), and a position over the ground (shortly before impact) where a steering calculation was done;


whatever starting point you chose to work from back around Aldergrove (ATC fix, V813, Belfast radar, or the apron at RAF Aldergrove) because that's 40 miles away it doesn't make significant difference to the track to waypoint A on the Mull (work out for yourself the bearings from wpt A to those spots, all within a fraction of a degree – this is the converse of how Robin Clark dismissed the points near the Mull as showing a change of track, as I understand his argument) – however, we are now looking for a change from a known point close to the Mull and therefore a small displacement can have significant effect;
firstly, to get to WPCHX they would have been following a track from Aldergrove to waypoint A and this is without doubt what the SuperTANS had been using to establish the track – this works out at 027 mag (it follows that the handling pilot would have been expected to have had 027 on his course selector to this point, something I will come back to);
within the GPS's own world (just that system) to have got from WPCHX to the position of the last steering calculation, the a/c track would have had to have changed 4.5 degrees to the right from the track that had got all the way from NI – as the Boeing analyst pointed out, this wasinto the (strong) wind and was therefore not just a result of drift after they had stopped steering towards waypoint A;
of course we only have those two points and the a/c need not have turned exactly at the first point so 4.5 degrees is the minimum turn – a few seconds later and the turn would have to have been a few degrees more – the required turn would have got to 8 degrees (a track of 035 mag) before they got near the shoreline, a figure whose significance will soon be made apparent.


Now the Doppler:
the Doppler system may not be all that accurate on its own for position fixing but it sure is good for very accurate derivation of track angle over ground, the velocity vectors in conjunction with the a/c heading with respect to the gyro compass do the job – and they had travelled over ground for several seconds by the time that the last steering calculation was made;
at the time of the last steering calculation, according to the Racal Rpt the system had a track of 026 T (2.12.2.1 – which was equivalent to 33.5 mag) but in section 2.10.4.2 they had thoughtfully adjusted the data to reflect that it was over land at that time (the system was still set at “sea”) and they got 028 degrees true – which was equivalent to 035.5 mag back then.
035 was the setting found on the handling pilot's horizontal situation indicator course setting – as he would surely have had 027 on it until near or at the position of waypoint change, he must have changed the course selector to the course that they then followed.


Talk your way out of that.
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Old 22nd Jul 2010, 08:27
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flip, SFFP, you are both right of course and I thank you for your concern, but there is a wider audience out there, never posting but nonetheless following this thread. Some of them may well be vital to this campaign but do not necessarily understand the tactics being employed by the likes of JP and caz. That is why I feel it important to disclose them. I must admit though that MOD apologists employing the AAIB inspectors as allies to their cause takes some gall, but that seems to be in never ending supply.
Dervish, you are right to focus on the Super Tans switch which Mr Cable of course felt must have been in the Off position before the crash from the soot patterns (classic professional accident investigator observation). Two questions follow at least I would suggest:
1. Was the Super TANS itself Off therefore or merely the display?
2. Why would the switch have been selected Off?
We have heard of the immaturity of this aircraft, particularly in this regard to its Nav fit. Was it SOP to simply not use the TANS because of radio interference, or merely to select Off if such interference occurred? Yet another example of how this BoI failed in its work that such questions should be asked 16 years later, and how such questions could still be asked by a proper Accident Investigation by the AAIB!
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Old 22nd Jul 2010, 08:51
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Walter Kennedy

I got the first bit but this is beyond me.

and we would not have had the clue of the switch being turned off after the crash.
Someone right there thought he was being clever by switching off the nav computer.
How did you leap to the switch being toggled after the crash, but before fire took hold? The AAIB evidence suggested it was off before impact. Are you saying someone was on site and risked their life to dash into wreckage strewn across a hillside, searched for a single switch and toggled it? Wow!

Sorry but I’m reading up on this as points are made. From what I can see it was Mr Cable who noted the switch being off, but Mr Parkinson who dealt with MOD and Racal over the analysis of the Tans unit. There seems to be a yawning gap whereby Mr Cable’s evidence is not addressed in the Racal investigation. The AAIB report comes to an abrupt end just as interesting questions are raised. Mr Cable doesn’t seem too impressed with MOD. A proper investigation would, as chugalug suggests, fill those gaps.
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Old 22nd Jul 2010, 09:22
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AFCS limits.......

Mmmmnice
[Robin - the cyclic is not physically limited to 2" aft on the ground - the limit is imposed to prevent droop stop damage when the collective is in the 'ground detent' (almost fully down) position]
..thanks for that...but I am still confused......the manuals read as though it is 'gated' and not just cautionary advice......and block diagrams of the Chinook AFCS show an input from the rear undercarriage........why does it need to know the state of the gear if it doesnt do anything...???????....

rgds Robin......
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Old 22nd Jul 2010, 10:03
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You'll just have to accept Mmmmnice's explanation, its true! Its to do with LCT programming and sensitivity of the pitch channel.
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Old 22nd Jul 2010, 11:54
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The Mythical Turn.....

Walter.......
...the request was for a list of co-ordinates you used........a diatribe about headings does not show anything....
..plotting all the GPS locations from the RACAL report , Aldergrove , waypoint change , last steering update , powerdown and the last unprocessed location from the Trimble GPS itself......you can see that they are all in a straight line.....Robin....
....plot them on a map or use software , I prefer a Garmin programme which I have , but Google earth will show the same......

rgds Robin........
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