Reckless endangerment?

[chopjock]

I would like to ask for any one's opinion on the subject of "Reckless Endangerment".

For example if I removed a door from my helicopter and strapped in a load across the floor that was hanging out the door a little, say two feet and weighed about 60 lbs.

Assuming the aircraft is within it's c of g limitations, and within it's max take off weight etc, and the load is 80% within the aircraft and quite secure and does not interfere with the controls and no modifications have been made to the airframe, would any one here consider this to be "Reckless Endangerment"? and if so to who? the aircraft or people on the ground?

[Barndweller]

I'm guessing that this is not a spur of the moment question...?

My initial thought would be that as long as 1) your removal of the door was iaw the flt manual (and company procedures) and you were authorised to carry out the removal. 2) all aspects of the Flt manual were complied with as regards floor loading, COG etc and that the flt manual did not prohibit cargo sticking out of the aircraft 3) the load was adequately secured, then i can't see how you would be guilty of reckless endangerment.

who thinks you were?

Barny

[spinwing]

Mmmm ...

Well if you then went flying and had an accident (or somebody in authority saw the a/c before you flew) .... and in the course of an investigation .... the investigators found that what you had done (ie loading the aircraft) had or would of significantly altered the flying characteristics of the aircraft (such as the ability to enter a 'steady state autorotation') then .... YES you may well be guilty of "Reckless Endangerment".


:}

[Genghis the Engineer]

It's one of the CAA's favourite criminal charges, but as a criminal charge requires proof "beyond reasonable doubt".

In the case stated, I'd ask some obvious follow-up questions:

- Is the aircraft cleared for flight with the door off?
- Is the load within the floor load bearing limit?
- Would any qualified pilot or ground engineer reasonably assume that the 2ft of load stuck out of the door and into the prop-wash would create no significant new downwash blockage or asymmetric drag?

If you can convince a jury (or more likely panel of magistrates) that the answer to all three is "yes", then it isn't reckless endangerment. I'd venture that the last question is the difficult one.

(Shame Flying Lawyer isn't able to talk about this stuff any more, he'd be much better than me on the subject - but for the record I've done 8 aviation court cases as an expert witness, one a defence from a CAA prosecution for just this thing - albeit after a fixed wing prang, and I also studied helicopter design to degree level.)

G

[chopjock]

Ok here's a little more information...

The aircraft is cleared for doors off flight and up to 600lbs or 3 pax in the front seats.
I have two certified engineers who's opinion is the aero dynamic shape of the load and the way it is secured is safe.
The aircraft flies in perfect trim up to VNE
I appreciate the comments, for and against. Please keep them coming.

[Nigel Osborn]

I'm sure most bush pilots have done this. However it was pointed out to me that the flight manual does not have a fuel flow figure in this configaration, therefore it is illegal.

[Agaricus bisporus]

Sadly without specifics - all of them - no one here is going to be able to help. Presumably you've fixed something to your Enstrom or Hughes 500 that someone thinks shouldn't be there, but withiout the what and how we're not going to be any the wiser.

My own advice from an eminent barrister specialising in aviation cases was that it is a brave individual who goes to court against the CAA as they seem to have the ability to blind a jury with both the ldazzle of their legal team (no expense spared) and their percieved might and righteousness as the Mighty CAA.

He was not at all confident in getting me off a charge of infringing the 1500ft rule while filming over an aerodrome on a specific CAA exemption from the 500 ft rule, despite the fact that he'd have coined in £000s for the case no matter the outcome.

Get the idea?

Taking off yer fibreglass rocket pods or whatever they are and telling them you'll accept a slapped wrist just might be the cheapest, though no doubt unpalatable option.


Good luck!

[ShyTorque]

I would say it wasn't reckless, provided you did a sensible risk assessment.

Like I did when I was asked to go out and bring home a large piece of an aircraft (inner flap from an almost new Boeing 747) which had fallen off in flight.

I was originally asked to carry it as an underslung load in a net. I assessed this as very dangerous - after all, it was a fairly lightweight piece of aircraft designed to produce lift and it therefore might well fly up and hit the aircraft or even into the rotor once we got under way (just like a complete Harrier wing once tried to do when the RAF tried to undersling one).

It was too big to fit in the cabin lengthwise. I agreed to fit it across the cabin, sticking some distance out of each sliding door, as long as it was tied down facing backwards and upside down. I flew it at slow speed (about 50 kts) and it was fine.

The local (non UK) Civil Aviation Department had no issue with this, in fact they saw it as a job well done. The task request was from them and two of their staff were on board throughout the task.

[Whirlygig]

The aircraft is cleared for doors off flight and up to 600lbs or 3 pax in the front seats.Schweizer 300C?

Cheers

Whirls

[Agaricus bisporus]

Hughes 300! Oh No!!

Dont say...!!

You've taken that bloody nimby woman from Norfolk for a ride by force and strapped her to a plank and wedged her face down out of the door so she could see what fun helicopters really are. Fnaaar!!!:ok:

There's little hope I fear, you'll get an ASBO and have to listen to her lawnmower from just 50 feet away for an hour at a time - so your quality of life will be utterly ruined too.:ooh:

[VeeAny]

Not commenting on this thread specifically but just to Nigel Osborne and purely out of curiosity.

I called one of the manufacturers a few years ago because their new model had no fuel flow figures or graphs like the old one did and they pointed out to me that they are not required to put them in the manual so they don't anymore.

The engine manufacturers are the ones who give the fuel vs Atmospherics and power setting graphs in their documentation and I can't see that changing at all in this case. There will (in almost every case) be a drag penalty to pay resulting in increased power setting and increase fuel flow, but if the airframe manufacturer doesn't need to publish it how can it be illegal in that context anyway ?

I am talking about an aircraft manufactured and approved in the US.

[Genghis the Engineer]

Let's hypothetically say that somebody is being charged as discussed, and it's by the CAA.

Now, if the CAA are unhappy about something, they have the full force of the organisation behind them. This means that if anybody is capable of finding an ANO infringement, they'll have done so.

So, if the charge does not include any ANO infringement, but ONLY reckless endangerment, this implies to me that they couldn't find one.


So, your barrister would probably conduct a discussion along these lines in court:

Barrister: "So, Mr CAA, you've reviewed the ANO, manuals, licencing regulations and so-on, and you've not charged my client with any breach of any UK regulations".

CAA: "That is correct, we've charged him with reckless endangerment"

Barrister: "So, you are saying that it is possible to recklessly endanger the public by fully complying with CAA regulations".


That, pretty much, was the course by which the chap I helped out got off his CAA sponsored criminal prosecution. And, in my opinion, appropriately so (albeit that the discussion above actually ran to about 7 hours).

G

[Miles Gustaph]

What a good question!

If I remember correctly to prove recklessness you need to prove 3 things:
There is an objective test where a reasonable person test is applied, I would suggest that in this case, “the reasonable Pilot” and would the outcome/consequences have been reasonably foreseeable by the reasonable Pilot… I haven’t done one of these for Pilots but in similar professional situations it often comes down to a bun fight with either side producing expert reasonable pilots who are there to respectively shoot you down or support your position. I would suggest that if “something” were to happen you might find it difficult to find a reasonable Pilot to support you.
There is also a subjective test where the court itself would try to establish your state of mind at the time of the “occurrence”. I.e. what you were thinking; if they came to the conclusion that you were aware of any risks it may not be beneficial to your case, and if there was an occurrence when you have done something “odd” to an aircraft it may be very difficult to convince the court that you thought everything was “safe”.
I think the final test is the first two weighed up together.To summarise, and again if I remember correctly if you are aware that a harm may occur as a result of your actions and you ignore it and do it anyway, I think the phrase wilful blindness applies here, you could be in for a hard time.

Trying to convince a jury and or a Judge that you did something and you hadn’t realised it would cause harm could be really tricky, I would suggest that civilians would always side with the voice that is on the righteous side of safety.

Rule of thumb, if your intent on doing this, do a risk assessment, detail what your going to do, reduce the risks as far as possible, if your still intent and cannot reduce the risk any further then all your left with is the known risk which can be foreseen, can you justify it? & latent error which cannot be reasonably foreseen.

[Hughes500]

The nub of this is " an ordinary person test " now comes down to risk assessment. Every time we take off from a confined area, approach a confined area we subconsciously do a risk assessment. The same can be said of c of g calacs, I have worked for 2 companies where one has chosen actual weights of pax the other average weights. You could argue that average weights is reckless endangerment, can certainly think of a few incidents where the pax were way heavier than average, but according to the manual ( CAA approved) we were legal
Basically the CAA would appear to be on a fishing exercise probably supported by an other helicopter company ( competition) who is feeling peeved, either wrongly or rightly.

[Miles Gustaph]

Hughes,

the "ordinary person test" is not the same as a risk assessment in this case.

The risk assessment is to mitigate if not remove all the "risk" you can, this is a much different situation to had you not carried out the risk assessment.

For example:
a) An accident with no risk assessment: it could be said that you deliberately and knowingly did what you did without taking any precautions to prevent it... not so good, back to your safe argument and juries being pro safety.

b) An accident: Having carried out a risk assessment and taken all the precautions possible, or that you could think of makes it is easier to say that you couldn't have reasonably foreseen the occurrence.

A risk assessment is a "block" in the safety chain, James Reasons swiss cheese model, that acts as a buffer to the actions of the end user.

So when the duty lyncher claims that you knowingly endangered X, you can say, "not so! I did a risk assessment, carried out mitigating acts that I believed would stop X, this was an unforeseen occurance/act, possibly due to a "latent" error ...etc bang goes a juries/ judges beyond reasonable doubt....well that's the plan!"

Rule of thumb number 1. if you cant justify it before you do it, don't do it.
Rule of thumb number 2. if you can justify it think again considering that when we mess up in aviation we quite often kill people.

[500e]

What is being hung out a tube, plank or camera, person ?
Is there a precedent ? do other people hang the thing out ? has there been an incident ?
Is the machine UK registered? if not does the reg authority allow the TPCP to be hung out, or does this not count with RE..
Lots of questions no answers :{

[SASless]

Whirls,

Barely squeezed in did you Sweets?

[ShyTorque]

Q: Would the driver of a road vehicle, such as a van, where the rear doors are left open to accommodate a long internal load, face a charge of "reckless endangerment"?

[Non-PC Plod]

Chopjock,

If its not a black & white, open & shut case, where there is no clear violation of a specific rule, its going to be down to who argues best in court.

I'm with Genghis on this one - sounds like you have a good expert witness if you need one there. If they cannot prove "beyond all reasonable doubt" that you acted in a way that was:
a) reckless, and
b) endangering someone,
they are not going to win. If you can show that you took reasonable sensible precautions, did the calculations, were within the aircraft limitations, ANO etc, how can anyone prove you were reckless? With an expert witness on your side to say you werent endangering anyone either, then at the very least you have created reasonable doubt, even if the CAA disagree.

[mickjoebill]

From an aerial camera operators perspective.
"We" can justify the mechanical probity of lashup camera mounts with a few engineers tugging and pulling at the thing. The rule of thumb is if the rigging fails will it effect flight? In some countries this kick the tires test is all that is required for permission for a particular flight. It helps if there are no welds or complicated cross bracing and the rig looks like it has a very high safety factor and simple WYSIWYG fixings.


However I think it reckless from a business standpoint, as in the event of an incident as the onus will be on the operator to prove installation had no adverse effect on
1/Aircraft performance- could the aircraft have made a successful emergency landing without the rig?
2/Crash worthiness- did the rig contribute to injuries in the cabin or delay egress?

For instance, a camera man was killed last year when the helicopter crashed during a shoot. Other occupants survived but the cameraman was pinned/crushed by a (fully approved) side camera mount.

Imagine the implications to this case if an unapproved mount was used.

In contrast in 2004 a cameraman died when his home made camera mount prevented him egressing the fixed wing that had to ditch. Three other occupants escaped but the cameraman was snagged on his own lash-up rigging and drowned.


From a moral perspective I consider it wrong if one is flying with others onboard (who are not aware that their safety if not their insurance! is being compromised) or when flying over a built up area with anything but an approved mount.

Having been through the process of commissioning designing flight testing and gaining CAA approval there are numerous engineering and legal gotchas that are not immediately apparent.

For instance, it is interesting to note that some helicopter manufacturers do not even rate the load capacity of in-floor cargo hooks, yet operators ratchet strap down precious cargo and then fly with doors off.

But the world of approved mounts is not all rosy.
There are varying standards of engineering and design with a range of design safety factors starting as low as 1.1.

One locally approved design in Scandinavia pays no respect to the notion that their can be a power failure as the bracket puts the camera so low if the camera is not tilted up for landing it actually touches the ground!


A common nose camera mounting point for the bell 206 and (I think ) 4 series uses fixings designed to retain nothing more than panels in an area where Bell did not envisage any exterior load. Bell will state that that part of the aircraft is not designed to hang cameras from yet their has been a number of mounts approved partially or wholly using these fixings.
To prove this particular example, after consultation with engineers and Bell a European operator went to the trouble and great expense of reinforcing the nose of his Bell 206 so he could fit a relatively lightweight 20kg gimbal.

Ditto the R44 side camera mount. Last time I enquired Robinson said that they do not recommend bolting cameras to the side of their R44 yet there is an approved mount to do so.

Aviation laws and their enforcement are inconsistent, but a few things are cast in stone when going off road with a lash-up mount.
You are as sure as hell not improving flight safety or heli performance and probably compromising crash survivability of the occupants and your business.

So maybe it is a little reckless?

Mickjoebill

[chopjock]

Some good points there Mickjoebill, in this "hypothetical" example, the door is removed and the egress is completely un obstructed. I have the opinion from two independent certified engineers that the (lash up) rig is safe.

Thanks to all for your opinions on this. This is all "hypothetical" at the moment and may or may not lead on to something else.
Lucky for me I had completed a risk assessment and double checked my weight and balance figures. :ok:

[Flying Lawyer]

Genghis the Engineer
Shame Flying Lawyer isn't able to talk about this stuff any more .....

It's a shame for me too - I wish I could.
However, if I could, I would have to qualify and/or correct some things you've said.

Please don't be offended. I respect your engineering qualifications. However, in legal matters as in many other fields, a little knowledge can be a dangerous thing. ..
The particular danger on PPRuNe is that, if advice appears to be knowledgeable, readers may accept it at face value. I've seen it happen many times over the years, although not often in Rotorheads.

(Edit)

chopjock
If you go ahead and are prosecuted, then your lawyers (preferably aviation specialists) should obtain expert opinion.
NB: From a helicopter specialist with many years of practical experience in helicopter ops - nothing less.
Anyone else could result in you losing a lot more than just the fees you wasted on your 'expert'.

FL

[Genghis the Engineer]

Genghis the Engineer


It's a shame for me too - I wish I could.
However, if I could, I would have to qualify and/or correct some things you've said.

Please don't be offended. I respect your engineering qualifications. However, in legal matters as in many other fields, a little knowledge can be a dangerous thing. ..
The particular danger on PPRuNe is that, if advice appears to be knowledgeable, readers may accept it at face value. I've seen it happen many times over the years, although not often in Rotorheads.

(Edit)

chopjock
If you go ahead and are prosecuted, then your lawyers (preferably aviation specialists) should obtain expert opinion.
NB: From a helicopter specialist with many years of practical experience in helicopter ops - nothing less.
Anyone else could result in you losing a lot more than just the fees you wasted on your 'expert'.

FL

No offence taken FL - I'm sure you and I would be on safe grounds in agreeing on one firm piece of advice: if this isn't theoretical and somebody is genuinely in some potential trouble, they really should go and consult properly, even if they have to pay for the advice, rather than trusting anything that they read on here.

G

[JimBall]

Chopjock: I see you are UK-based. And I'm wondering if the device you refer to is the LSG ? This US-made product is a gyro-stabilised mount for any camera - not a ball.

I ask because I know that a certain FOI has made it his duty to ensure that the mount is not used in the UK because he believes that it should be EASA-approved, even though it is not clamped or bolted to the airframe. It straps to the floor and there lies the problem, apparently.

[chopjock]

Does anyone think a load strapped to the floor that overhangs the door frame a little requires a certification?

[Oldlae]

IIRC anything outside the aircraft that might be used as equipment needs a major modification as it has to withstand the slipstream without being disturbed. It is doubtful if a lashed down part would be accepted. BTW I stand to be corrected.

[whoateallthepies]

Forties Field Shuttle with a Dauphin we used to do it all the time in the eighties. (Didn't we Griffo?)

If it didn't fit in the cabin it would be securely lashed down and protrude with both sliding doors pushed back. What's the problem? Obviously no passengers allowed on the same flight. A fuss over nothing.http://i334.photobucket.com/albums/m412/omanjohn/2637784011.jpg

[spinwing]

Mmmm ....

As per OldLae's quote above ... which brings me back to my post #3 at the beginning of this .... no doubt the persons bringing this charge may well prove that the flying characteristics of the a/c MAY have been varied (and they may well test fly an a/c to prove same) .... this in itself I would predict would prove a lack of knowledge in preparing the a/c for flight and thus would constitute recklessness ....

Good luck :ugh:

[Legalapproach]

My own advice from an eminent barrister specialising in aviation cases was that it is a brave individual who goes to court against the CAA as they seem to have the ability to blind a jury with both the ldazzle of their legal team (no expense spared) and their percieved might and righteousness as the Mighty CAA.

I don't know who you spoke to but I profoundly disagree. I have defended a number of cases against the CAA and have not lost a single one in recent years. The interesting thing about the CAA is they do not use "aviation" lawyers to prosecute. i.e. lawyers who are qualified pilots or who have practical experience of aviation matters.

One even once told me "The Authority offered to arrange for me to go flying but I told them you're not getting me up in one of those things."

It is extraordinary how often cross-examination of the CAA experts by someone who is conversant with aviation practices completely reverses their case with the prosecution simply not seeing it coming. I don't in any way seek to criticise any individual lawyer, in my experience they have been experienced and good criminal barristers - just not pilots or total or even partial aviation people.

I would hesitate to give any opnion on this case without a lot more information but I echo what FL says, you need to get a good aviation lawyer with access to good experts.

[Oldlae]

Pies, I think you are talking about cargo, I think this is about equipment being used during flight. OTOH I could be wrong.

[Flying Lawyer]

FL - I'm sure you and I would be on safe grounds in agreeing on one firm piece of advice: if this isn't theoretical and somebody is genuinely in some potential trouble, they really should go and consult properly, even if they have to pay for the advice, rather than trusting anything that they read on here.
That's what I said in my previous post. However, chopjock says it's hypothetical at the moment so there's no harm in asking for advice here.
Don't under-estimate the knowledge and experience of the professional helicopter pilots/engineers in this forum.
Someone may even have encountered the issue he's raised and be able to tell him what he needs to do and/or should not do. He says it may or may not come to something. If it does, then it would be a wise precaution to obtain an expert opinion in writing before proceeding further.

Whether for advice before final decision re going ahead, or in the event of a prosecution, it is absolutely vital that the expert should have relevant expertise and experience. eg There are some aspects of aviation in which I would have been very happy to use you as an expert, but obviously not for something like this.


Legalapproach
you need to get a good aviation lawyer with access to good experts. A non-specialist solicitor can be enough in some instances provided the barrister is a specialist, but I agree a specialist team is obviously better. (For several reasons.)

Agaricus bisporus
Assuming that is exactly what the barrister said, I too was puzzled by the advice you were given by the "eminent barrister specialising in aviation cases."
There were occasions when I advised a pilot to plead guilty, but only if he had no defence. I never had any difficulty coping with the CAA prosecution team. What you describe seems odd.
It's correct that clients are sometimes worried about "going to court against the CAA" and I suspect magistrates or juries may well start off assuming that what you describe as the "Mighty CAA" must know if something is legal or illegal because they are the regulators. However, I never found that to be an insurmountable problem.

.

[Hughes500]

JimBall

Which FOI out of interest ? The mount looks ideal really and as it not attached to the helicopter I dont really see what he can do about it otherwise he will be after Garmin GPS with suction mounts !!!

[chopjock]

Gentlemen,
I am led to believe this hypothetical situation will not develope into something more serious with regards to "reckless endangerment", having had a visit from the campaign. However now another situation exists which I think is open to interpretation.
According to my two certified engineers, this load is only being carried and makes no difference whether it is switched on or not. According to them no modifications have been made to the airframe, so no certification is required. However the campaign says different. Does anyone know where in the ANO can the relevent rules be found on this? ie, it's deemed ok and acceptible to carry rotor blades over hanging the rear doors and strapped in across the cargo deck whilst recovering a downed heli, but it's not ok to hang something else out the door that can be switched on and is secured in a similar manner? :ugh:

[mickjoebill]

There are a few sit on the seat stabilisers which are a challenge to rig as securely as say a Tyler side mount.

The new ones draw attention from engineers as they are neither a hand held camera nor are they an approved item which is secured (from an engineers perspective) to the airframe.

Although the concept of a cameraman leaning out of a door holding a tethered camera is acceptable a 30 kilo apparatus that is top heavy and can usually only be secured at the base by straps, raises concerns with engineers.

On one hand it is safer for the operator to be well inboard operating a sit on the seat mount, rather than hand holding a camera near the open door.

On the other hand the top heavy sit on the seat mount is dependent upon adequate straps to prevent it swaying around in a heavy landing or something more serious.

A safer option is to install it on the floor but this often restricts the angle of view.
I wear a helmet when operating this type of kit in any moving vehicle.

I can't see any reason that they need to be certified anymore than the piece of string tethering the camera to the airframe when hand holding.

One eminent still photographer I know hand holds a very heavy DSLR with 600mm 35mm lens without as much as a strap.


Mickjoebill

[mickjoebill]

Few pieces of carry-on equipment that are plugged into comms or power are certified, ie cellphones, cd players ect.

The AS 350 and the robbo encourage the use of accessories by providing accessory sockets.

Most of the spinning mass gyros fixed to these mounts can be run on batteries anyway.

Is campaign saying that nothing can be switched on in the cockpit that is not approved? so use of a laptop is banned? a camcorder?
FAA released guidelines for electrical carry on kit in FADEC aircraft, their main concern is high power RF transmission aerials installed closer than 1 meter to the FADEC computer.

But well intentioned engineers baulk when we turn up with a collection of electrical kit to install into their Fadec heli. Generally they are ill informed.


Mickjoebill

[Freewheel]

I'm sure i've seen photos on here somewhere of a 206L's doing a coffin charter with both ends external to the cabin profile.

Relatively common in PNG.

[JimBall]

mickjoebill: I think the problem chopjock describes is a "cargo" problem rather than electric load. (Although quite how anyone can safely plug gyros into a 4-amp rated R44 cigarette socket is beyond me....)

A lot of computer-based equipment (like FADEC systems) is susceptible to voltage drop - and the drop encountered when gimbals and gyros are switched on can cause a flutter even with a totally healthy alternator.

As for your stills photog friend and his unrestrained camera........maybe that's why we need alert FOIs !

[chopjock]

Hughes500 JimBall

Which FOI out of interest ? The mount looks ideal really and as it not attached to the helicopter I dont really see what he can do about it otherwise he will be after Garmin GPS with suction mounts !!! If it's the same FOI that threatened to charge me with Reckless Endangerment over the phone then his first name is P:mad:

A good job my heli is not a FADEC system then.

[kevin_mayes]

Hey, Guys.

If this is about camera mounts, then why doesnt anybody make one that sits in a dumpy bag, and can be slug on the cargo hook? with modern gyro's that would/should be possible especially if you use IR to control it, then the item would be just an underslug load - no certs required?

Ok, I'll get my coat....

Kev.

[Genghis the Engineer]

Whether for advice before final decision re going ahead, or in the event of a prosecution, it is absolutely vital that the expert should have relevant expertise and experience. eg There are some aspects of aviation in which I would have been very happy to use you as an expert, but obviously not for something like this.


I'm not sure at the moment that it's entirely clear what "something like this" is at the moment. If it's common helicopter operating practice, then you're absolutely right. If it's aircraft design approval legalities, you probably aren't - and if it's helicopter aerodynamics, then I can certainly hold my own but if it was the core of a task, I'd certainly defer to somebody much more experienced (as I did quite recently in fact over something related to a helicopter accident issue which related to blade dynamics - the chap who originally taught me my helicopter aerodynamics had a lot of fun with the task I believe.)

G

[chopjock]

Well the campaign could not find anything dangerous with the "bracket" but ordered the aircraft not to fly with it fitted until it gets certified.
Good news, I now have the bracket certified. Turns out those that made the complaint have actually done me a favour.:ok:

[Heli-phile]

I remember buying a baggage pod for my MD500 and was pleased to hear of the pragmatic way most mods are designed, tested and approved.
If you have developed an item to attach to your machine, get an engineer to inspect it, sign it off as fit for purpose and then have an experienced pilot flight test it and check for adverse effects.

For example the pod I bought was deemed fit for purpose and the only handling issue experienced was a slight instability during an auto with a high rate of descent. So placard was added and supplement created prohibiting speed above 90kts in descent. Seems fair enough!!

Sounds like you have gone down the mod route now(best idea) Anyone who starts bolting bits onto aircraft leaves themselves open to legal action rightly or wrongly. Also never forget our friends in the underwriters department. If your mod and its host ever do end up in a pile (even if totally unrelated to your mod) the underwriters might very well feel your modification gives them valid grounds to withhold both your and your 3rd parties claim:(

Modifications are a brilliant aspect of aviation development, keep thinking them up everyone, even if the paperwork might seems excessive, in the end it protects everyones interests.