How long does it take to trim from full nose up to take off trim or nose down trim in a FU24. I've heard that it can take several seconds and many many winds of the trim handle though I'm not sure if this is correct.
I suspect that TAIC have rightly concluded that the trim position was academic. We'll never know for sure anyway.
The clue is in their report:
"On the accident flight the centre of gravity of the aeroplane was well rear of its aft limit and it became airborne at too low a speed to be controllable."
Not slightly rear...
And, of course, unlike a hopper full of super, this cargo could, and almost certainly did, move. Whether there was much room or not, everybody piled against the rear bulkhead will obviously result in a far more rearward C of G than if they were evenly spread throughout the cabin - all the more critical when the load is rearwards of the spar.
As I mentioned, we'll never know for sure whether it was the chicken or the egg, but either way, there were serious deficiencies in the operation.
"On the accident flight the centre of gravity of the aeroplane was well rear of its aft limit and it became airborne at too low a speed to be controllable."
The question being why was it well aft of the rear limit??
As previously stated this aircraft had carried out a number of sorties without any obvious problems. The load in itself was not excessive, in as much as the pax were not unduly heavy. To put the C of G well aft on this particular flight, far enough so as to be uncontrollable, some of the load must have moved either just prior or during lift off. The question is then why? and any answer to that question can only be speculation.
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How long does it ta ke to trim from full nose up to take off trim or nose down trim in a FU24. I've heard that it can take several seconds and many many winds of the trim handle
It does take a number of turns, from a dim memory maybe 10 to 12, but it can be done in a very short time, 2 or 3 seconds maybe, there is no load on the trim handle.
Last edited by prospector; 14th May 2012 at 04:02.
3.5.4. An elevator trim system was fitted to assist the pilot and ease elevator control forces when operating in a range of speeds and loading conditions. Fletcher aeroplanes had either electrically or manually operated trim controls. The trim control for ZK-EUF was manual, with a rotating handle located on the left side of the cockpit, aft of the power-control lever (see Figure 6). The trim could therefore be moved with the pilot’s left hand while at the same time the right hand held the control column. The trim took about 25 turns of the handle for full travel.
The aircraft obviously pitched up on rotate, possibly even slightly before. The investigator knows how to fly an aircraft, many here have worked alongside him. I am sure he would have a fair idea or perhaps a personal belief. He is much closer to the action than any of us. I would have thought the pilot, yes I knew him also, would have been very busy with the felt hand. pitching up with low airspeed..... hmmm I think whacking full power on would be high on the list of priorities, or at least confirming full power if that is the Walter system. 25 is the maximum number of turns so I guess 15 would be a good guess from landing to fully nose done. Still a lot of cranking to do when the nose is already pointed well above the horizon. Perhaps the pilot did manage to crank all the turns in but by then the aircraft was already doomed. The C of G would have caused a crash sooner or later. It truly is the Swiss cheese sequence yet again.
I also can't believe the operator did not at least have a series of standard W&B sheets prepared and approved. ie, Standard loads with various trip fuels.
I operate both NZ and Australian engineering licences..... the NZ is very good for normal GA operations. A lot of reliance is put on the IA and unfortunately this one and the balloon tragedy are not helping the industry. It would appear the IA in each incident may have a case to answer.
The operations should be a lot more professional than these appear to have been. I am sure we will be seeing some increased audit activity there also. You have to feel for the families, this report must be difficult reading.
The father of a young man killed is quite right, we are amateurs. In my experience the response from the CAA to reporting a safety issue is defensive. Others have had similar treatment.
Is there going to be a report to the minister or Parliament when the CAA has its house in order?
I hope the emphasis is showing people how to get it right, in broad terms, when a proposal is made for an operation. I remain unconvinced the key to safety is paperwork, however necessary that might be.
That 60minutes story was the biggest load of one sided 'pony pooh' seen on TV for sometime.
There was not one mention of the changes & introduction of part 115, which has introduced a raft of safety measure's including a calculated W&B for each load minimum experience and recurrent training. Which is far more than a drop pilot in oz gets.....
Having worked on both sides of the ditch recently, NZ has a much better regulatory system to work under & a far more approachable regulator.
I agree that the NZ system is possibly better than the way things are done in Oz. I figure with SMS and good surveillance and industry education promoted by regulators, terrible accidents like this can be prevented. We are all responsible for aviation safety, not individuals.
The so called story shown on Australian 60 minutes was, as far as the accident goes....rubbish. But what else could you expect from the media. They just don't seem to be able to do any proper research on anything to do with aviation.
No words can possibly describe what the victims families have been going through for the past two years. My comments here relate only to the actual accident.
I find it mind boggling the CAA can just turn around and blame EVERYTHING on the pilot and operator. I honestly didn't know that was their opinion.
60 minutes based their story on the TAIC report. The opinions of their expert were based on the TAIC report.
Would it surprise anyone to know that in an investigation into an accident in which Nine people lost their lives, that not all of the aircraft was recovered for proper investigation.
No person in the investigation team had even the slightest knowledge of the Fletcher FU24 type aircraft. There were plenty of qualified people available who did, including qualified accident investigators and engineers with enormous experience on type, but their services were apparently not required.
The accident was clearly a loss of control accident. The control column was found to be broken off and was found in the cockpit. The control lock was torn out but not found, even though it is clearly visible in photos post accident.
These items were buried on site along with the remains of the fuselage and wings. No proper testing was carried out on the control column or lock, such as testing by appropriate persons as to what caused the fracture, or why and how the lock was torn out. DSIR I imagine could have studied the control column?
A few months ago an exact same control column (cresco) broke off in flight, luckily the aircraft was dual and the pilot was able to land safely.
There is so much wrong with that report it is not funny.
Anyone who watched the Coroners inquest, which was screened live, and hearing all the expert witness's, should be convinced that C of G had no part in the CAUSE of this accident. Although even when faced with overwhelming evidence some "experts" refuse to change their opinion. Seems to be quite a few on this site who are quick to lay blame with absolutely NO knowledge of this accident. The Coroners report has not been released yet.
In independent CAA approved and monitored flight tests, in the same type of aircraft, with the same load and C of G position, the aircraft was fully controllable in all flight conditions. It didn't matter where the trim was set, it could be fully aft, the aircraft was still easily controllable through all stages of the take off. The aircraft had strain gauges and inclinometers fitted. All testing was carried out by a qualified test pilot and design engineer, it was done bearing in mind the average pilots ability. This is all documented.
The aircraft had completed 78 previous flights with the same loadings with no hint of being marginal, it flew perfectly. Other aircraft of the same type have carried greater loads in the skydiving industry for thousands of flights over more than ten years with no problems whatsoever. None of this information was taken into consideration.
We will now never know what the primary cause was, but in my opinion it was either a control breakage or jam of some sort, and beyond the pilots capabilities to regain control, even though he did manage to get it back to level flight and facing back towards the runway on a north easterly heading before the final wing drop.
even though he did manage to get it back to level flight and facing back towards the runway on a north easterly heading before the final wing drop.
Though the TAIC report claims a different flight path with no recovery, 2 or 3 of the eye witnesses called at the coroners inquest provided the above account viewed in detail from different parts of the airfield. Turns out, these witnesses were never interviewed for the investigation even though they were probably the most qualified (tandem masters and Pilot) and could give the most detailed and accurate accounts of what they saw.
The quality of this TAIC investigation stinks like that of the ATSB investigation into the Westwind at Norfolk. Poor.
A final conclusion made even before the investigators turned up at the site.
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Hmmm, I wonder what CAA were doing getting involved in this flight testing?
For a start, at the inquest the CAA's chief investigator essentially got up and said the TAIC report was crap and that W & B was not a causal factor. Perhaps the CAA wanted to back this up by going out and getting hard evidence through flight testing ? (something TAIC never bothered to do)
A final conclusion made even before the investigators turned up at the site.
Hit the nail on the head there L.M. Also they didn't arrive at the scene until a day and a half after the accident. Not good enough.
Because of the nature of the flight testing I would assume it required CAA approval. The fact is this testing should have, and could have been undertaken by TAIC, if they were interested in finding the true cause of the accident.
For a start, at the inquest the CAA's chief investigator essentially got up and said the TAIC report was crap and that W & B was not a causal factor. Perhaps the CAA wanted to back this up by going out and getting hard evidence through flight testing ?
Could it also be because CAA allowed certification from the Ag category into the category used for the skydiving operation without following all the correct procedures?
I suspect they were trying to cover their backside against potential legal liability by attacking the TAIC report and getting involved in the flight testing. Who actually instigated the flight tests Weheka mentions?
I agree there was some unseemly haste with parts of the investigation and TAIC missed the mark in some areas. Examination of the control column etc would certainly be helpful though I don't think this is the root cause but maybe a subsequently contributing cause.
There is no question the aircraft was being operated outside the C of G envelope. This might be OK when things are normal but when something out of the ordinary occurs then it could well be the straw that breaks the camels back. The flight testing proves nothing in my opinion.
Examination of the control column etc would certainly be helpful though I don't think this is the root cause but maybe a subsequently contributing cause.
So if the control column broke off at lift off or just after you don't think this would cause an accident? You are aware it was a single control aircraft?
Do you think any other Aircraft Accident Investigator in the developed world would dispose of these critical items without proper examination in such a major accident?
Why wasn't the control lock even found? It is plainly visible in the photos. Did they not know what it was?
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The flight testing proves nothing in my opinion.
Hard to believe anyone could seriously think that. Hopefully your opinion doesn't count for anything in this case.
So if the control column broke off at lift off or just after you don't think this would cause an accident? You are aware it was a single control aircraft?
In a properly loaded aircraft that was trimmed correctly, No,
Sure a broken control column would have resulted in a crash landing but in properly loaded and trimmed aircraft, it shouldn't have have resulted in the attitude this aircraft was reported to have assumed just after take off thus resulting in the impact that happened.
All the flight testing proved was the aircraft could be operated adequately in an aft C of G situation under normal conditions nothing more nothing less. I think it's safe to assume that conditions for the accident flight weren't normal.
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Hopefully your opinion doesn't count for anything in this case.
You're right, my opinion counts for nothing in this case.
It will be interesting to see what the Coroners report says.
Hard to believe anyone could seriously think that. Hopefully your opinion doesn't count for anything in this case.
Counts about as little as your opinion. Perhaps you could advise what your aeronautical experience is that enables you to come out with such profound statements.
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In independent CAA approved and monitored flight tests, in the same type of aircraft, with the same load and C of G position, the aircraft was fully controllable in all flight conditions.
It may well have been, but it is not the load and C of G that is likely to have caused the problem. It was the position of the trim control at the commencement of the take off run, and at lift off, in conjunction with the aft c of g, which would have caused a major pitch up, and caused the pax to move even further aft and accentuate the problem until it became not recoverable.
Having been caught a few times myself, not remembering to reset the trim from the landing position to take off position, I am well aware ot the stick load that has to be overcome to keep the nose down at lift off. The FU24 has a large elevator trim tab, combined with a fully flying tail plane creating a very powerful force if not trimmed correctly.
The question that will never be answered is why the aircraft pitched up to 45/50 degrees after lift off, forget vertical. Some unknown event caused this.
Another important piece of information that was ignored is this.
In my view the aircraft is most vulnerable to running out of forward stick when on the jump run. The aircraft is relatively slow, low power setting, and the first pair to exit have to come back to the door at least 12 to 18 inch's. The pair at the very back are the second to exit. This is where you would expect the aft C of G to become evident, and yet there was no problem. On ratings in the Fletcher, and I would imagine the Cresco and XL as well, this is something that is pointed out, to monitor speed and nose attitude on jump run.
On the other hand take off is perfectly normal. Take off with trim a couple of turns back from fully forward, after take off get rid of flap and trim back to about 3/4 forward and then pull nose up to maintain the 90 knots for best initial climb. Not something you would be doing on 78 previous flights with a similar load in this particular aircraft, and tens of thousands in other aircraft of the same type if the flights were barely controllable as TAIC suggests.
It may well have been, but it is not the load and C of G that is likely to have caused the problem. It was the position of the trim control at the commencement of the take off run, and at lift off, in conjunction with the aft c of g, which would have caused a major pitch up, and caused the pax to move even further aft and accentuate the problem until it became not recoverable.
I am certainly no expert, maybe you need to talk to the people who conducted the test flights, because according to them, with the same weight and C of G position as the accident aircraft, even with full aft trim on take off, the aircraft could be controlled with one hand on the stick as long as speed was below about 90 knots.
I don't think there would have been any load shift until a very late stage of the climb.
The question that will never be answered is why the aircraft pitched up to 45/50 degrees after lift off, forget vertical. Some unknown event caused this.
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That statement is correct, it will never be known with certainty. But I can say, after some 7,000 hrs flying FU24 on Ag Ops, with many thousands of t/o's, that the behaviour of the aircraft immediately after t/o points very strongly to the trim being left in the landing position and not set for t/o.
Last edited by prospector; 10th Oct 2012 at 07:50.
