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AAIB report on R/C Harvard published - attached as .pdf


John Lee
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No injuries, I suspect very little in the way of damage to the vehicle, any loss that the third party may suffer would be covered by insurance.

Don't get me wrong, but writing an accident report involving a model aircraft in the style of a full size piloted aircraft crash I find concerning. Yes, an incident of this type needs to be evaluated but in a proportionate manner by people who understand the issue and have great experience of the modelling world.  A thin end of a wedge if this type of thing gets into the media and twisted and amplified beyond all reason. AAIB do a great job for full size aviation as anyone who's watched 'Air crash investigation' on TV will have seen. OTT to have them looking into a few kilos of balsa, ply and fibre glass IMHO.

Edited by Cuban8
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I understand why people are worried about reporting such incidents, but we are required under our Article 16 Authorisation to report "accidents and serious incidents".

Since it involved hitting a commercial vehicle outside of the club field there is always the possibility of it becoming public knowledge, and not reporting it would them look like (a) a cover up, and (b) failure to comply with our Article 16 Authorisation.

Not a good situation either way!

 

Dick

 

Edited by Dickw
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I read this the other day and did rather roll my eyes. If it hit the lorry hard enough to destroy the model then i really doubt the engine was still running. 

 

The problem with these 'investigations' is that there is no actual investigation. It was all done remotely with no actual contact with AAIB. Seems rather a waste of time i have to confess as we dont actually learn anything. 

 

As has already been mentioned, sounds to me like the failsafe didnt operate if it was even set i the first place. 

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1 minute ago, Martin Harris - Moderator said:

92” span at 12 lbs take-off weight - I wish I could build that light!

 

I wonder if a damaged servo was giving the impression to the witness that the engine was running?

 

Or the witness had some sort of agenda? Who knows what the relationship is between these two groups. One side is accusing a shoot down so its possible they dont like each other much

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Not wishing to play devils advocate but the AAIB have pointed out in the past that a 10 lb weight travelling at 40 mph would considered 'dangerous' and potentially 'life threatening'. In an industrial environment such a potential risk would require positive protection for those in the vicinity.  The problem with RC is just how big is the vicinity?  

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This incident was correctly reported. It was suggested that the industrial area usedsome kind of jammer to prevent mobile phone use and also initmated that 'walkie talkies' used on site had the same frequency. The building and roof are all steel. Failsafe do not overcome gravity. The model hit the rear doors of a parked unattended articulted trailer. Other models have suffered similar radio brownouts in that particular area on varying occassions. The pilot is very experienced. Whilst pilot error is always a consideration how many of us have lost/crashed a  model and never had definitive proof of its cause.

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37 minutes ago, Zflyer said:

Failsafe do not overcome gravity.

True but the failsafe (FS) did not cut the engine to a tick over as it should, the report says it continued straight and level at half throttle. This is a bit worrying as it looks like FS was either not set or incorrectly set. The incidents that I have witnessed where the model has become unresponsive has resulted in the engine being (FS) and nose diving to ground, there has been no straight level flight at half throttle as is the case here. As you say the reason for the loss of signal is very hard to find as everything works as expected when tested after the crash.

 

The FS didn't work and we have learned nothing as @kcsaid. I wonder if this will be the normal pattern that future incidents will follow. 

 

 

 

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Are we relying on the witness who claimed the engine was still running after the aircraft “was destroyed”?  It sounds like one of our contributors has inside knowledge and might be able to confirm the state of the radio after impact?

 

A model at tickover with controls at neutral could quite feasibly glide for some distance, especially if “clean”.  As it hit the lorry, we might reasonably assume it was on a gradual descent rather than level flight? 
 

It would be interesting to know if the opinion of other model flyers at the field was sought?  They would be likely to be able to provide better witness testimony than a non-flying bystander. 

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I was going by the description -presumably from the pilot - that the model continued to fly straight and level at half throttle after his losing communication with the model, as indicating that the failsafe either hadn't been set to idle, or hadn't activated correctly.

 

I find it difficult to think of a reasonable explanation for the witness account that the motor continued to run after destruction of the model. That does not appear tenable.

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The question that should have been asked and answered is did anyone check that the failsafe worked when the remains of the model were retrieved.   Or was the Rx so smashed that it wasnt possible to test it?   Normally a Rx does not suffer damage to the electronics and would still retain the failsafe setting when retrieved.

The report didn't contain enough info to help prevent other accidents ( surely the purpose of the system! )  I would want to know the make of radio and it's history ( modified or not and whether crashed before) number and length of flights that day ( i.e Rx battery life ), was the Tx aerial pointed towards model etc.    All more important than pilots age and the fuel mixture!

Edited by kc
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In addition to the other items I mentioned I would have liked to know whether the switch harness and battery leads etc were examined for evidence of black wire corrosion ( to deduce whether Don's comment of switch or power failure was probable cause)  We have not heard much of black wire corrosion recently but it's still possible especially on older switch harness etc. 

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We will never know. Even the basics are in dispute. The report says it hit the side of the trailer. Z Flyer says it hit the doors. An experience flyer, lost contact with an aircraft, no explanation if the after flight observation was the expected failsafe position, or not. Voltage tested before flight, no evidence as to load testing of batteries. 
I'm not criticizing. I had one go in, faulty receiver, with telemetry, dead to command, and I switched the transmitter off, and lost the telemetry data, before the thing hit the ground. New to telemetry is my excuse. Faulty receiver diagnosis was further pain. 

Just bear in mind, the writer/investigator of this report is an apprentice, learning the form/shape of the paperwork.

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The damaged prop could prove this - if one blade remained intact then it didn't run after the crash!

 

It seems to me that if we have a crash that involves reporting to CAA we need to have the club safety officer to examine the remains to check and report on every aspect.   Unfortunately the typical reaction to a crash of any kind is to shove the remains in the car and not investigate the cause.   This is understandable but might go against aeromodelling in the current era.    We will need the facts to be recorded in order to refute any incorrect witness statements.

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I suspect that one of mine did some years ago - Mustang based Reno racer which I was showing off a bit with and did a low pass at less than propeller radius...pulled up, closed the throttle as soon as I realised it was all noise and no go and landed ahead in the next field with no further damage after leaving both blades and the radiator on the runway.  I did hit the throttle cut at some stage though - probably after the landing but definitely before retrieval.  However, the likelihood of an engine continuing to run after a frontal impact must be vanishingly small.

 

Back strictly on topic, this really does illustrate that the CAA are apparently paying lip service to investigation of reported incidents. As others have pointed out, nothing of any use has come from this and it just leaves many times as many questions as answers.

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