Helicopter Ground-Runs Performed by Engineers/Mechanics

[Saint Jack]

The recent AS350 accident in Brazil where the helicopter was destroyed on the ground by severe vibrations after landing brings to mind the perennial question of helicopter engine ground-runs being performed by engineers/mechanics. I had expected the thread on this accident to drift into this topic, but it seems to have faded away first.

When the question is asked, the most common and instant reply is "it isn't allowed", but when you ask for the authority of this reply you usually get a deafening slience or "we never do it". The next most common reply is "what if you get into ground resonance, you can't take-off to correct it".

Let's clear up the first reply, "it isn't allowed". Generally, only two parties can say this with total authority; a) the helicopter owner and, b) the helicopter insurerer, both for quite obvious reasons.

I only know of one country where legislation specifcally requires helicopter engine ground-runs to be performed by an approriately rated pilot.

In my previous company, nominated senior engineers/mechanics were trained and authorised to perform engine ground-runs, with limitations of course (no raising the collective etc.) and this was a boon to the end-of-day routine when engine washes and/or minor maintenace was required and there was no lengthy waiting for a pilot. The pilots were happy and the engineers/mechanics were happy.

I wonder, how many other helicopter operators out there allow engineers/mechanics to perform helicopter engine ground-runs. How is this administered and what are the limitations etc.?

[Senior Pilot]

Mechanic fatality Orlando (http://www.pprune.org/rotorheads/211733-mechanic-fatality-orlando-merged.html) is a thread from 2006 where just this problem occurred, with a fatal result.

[before landing check list]

With the possibility of that ground resonance situation or the possibility of a hydraulic problem resulting in the collective going up or a mis-rigged collective bungee/spring, maybe ground runs should be limited to idle unless you have an appropriately rated pilot at the controls.

[Turkeyslapper]

From where I came from, the only things the engineers could ground run in the helicopter was the APU, definately not engaged rotors engines runs.

[Fareastdriver]

One amusing one.

I had a shout from ops to go down and rescue some engineers who were sitting in a Puma burning and turning. I rushed out there and there were these two engineers with panic stricken faces sitting in a 330J with one engine at ground idle and the rotors slowly turning. They had got in to do a post chemo vent run and had inadvertantly started the engine and didn't know how to shut it down.

For those not familiar with the Puma there is a start panel underneath the instrument panel which has two engine switches. The first movement runs the starter motor and continuing to the spring loaded start postion starts the automatic starting cycle. To stop everything one has to position the switch back to the off position. They didn't know that; they only knew the run and off positions. They had inadvertantly move the switch to start and they were afraid to touch anything when the engine lit up.

A slight amendment to the brief for vent runs and it didn't happen again.

[Devil 49]

Previous employer allowed trained and approved mechanics to do ground run-ups. My recollection is that the aircraft had to be tied down to the pad. Aircraft were routinely tied down at end of shift, etc. anyhow. Most of the maintenance there was done at night, no pilot available. Worked very well.

[mtoroshanga]

For years I carried out ground runs as an engineer on various types including Bells throughout the range and non rotor engaged Alouette runs.
The criterion was that we could carry out runs on skidded aircraft without restriction. I was surprised to see that aircraft enter ground resonance as it is skid equipped however as far as I remember is equiped with dampers on the skid struts which could be the cause.
Ground running of aircraft used to be an engineers normal task, I cannot see the problem except that on entering ground resonance lifting into the hover is the first solution. I personally would be confident to do this but am sure that the way things sre now..........

[twisted wrench]

Last time I was in Norway in 2006 the CHC Norway engineers ( who had the training) ran the S-92 aircraft and probably the Puma to. They did both with rotor brake on and right up to fly position runs rotors turning.

They told me they went to Flight Safety ( S92) for training on running the aircraft and any emergencies they might encounter during a ground run.

I feel with the correct training there is no reason why the engineers can not run the aircraft. Is quite common practice in the fixed wing industry.

I agree makes the pilots and engineers both happy.

[Matari]

I still have my ground run authorization card (somewhere) allowing ground running of 206's up to the B212.

I do remember an exciting incident offshore when one of our mechanics was running a 206 on the deck, pulled pitch somehow and found himself 15 feet high and spinning. No choice but to point the nose down and get the thing straight.

After a few wobbly trips around the pattern he managed to set the ship down safely, no worse for wear except he was docked to junior mechanic and owned a great bar story.

His explanation was something about a lifevest being under the collective, and he tried to remove it, and oops...up came the collective. A likely story! :}

Ever since then we had to ground run with the ship tied down, offshore or onshore.

[Wizzard]

I do remember an exciting incident offshore when one of our mechanics was running a 206 on the deck, pulled pitch somehow and found himself 15 feet high and spinning. No choice but to point the nose down and get the thing straight.

After a few wobbly trips around the pattern he managed to set the ship down safely, no worse for wear except he was docked to junior mechanic and owned a great bar story.

Sorry mate you've got the date wrong, today's 1st March not 1st April!

[ShyTorque]

I feel with the correct training there is no reason why the engineers can not run the aircraft. Is quite common practice in the fixed wing industry.

But fixed wings aren't flying until they're doing a rate of knots. A helicopter can be damaged very easily during a rotors turning ground run by a poorly managed cyclic position, let alone by getting airborne and losing control of it.

But if someone else gets trained up to do it so I don't have to go in on a day off or midnight (done both a lot more than once), I'd be more than happy. Provided they didn't knock the hell out of the droop stops or chop the tail off in the process. :)

[SASless]

Engineers don't like Pilots twisting spanners.....Pilots should not like Engineers moving engine or flight controls.

Plus....it is job security and impacts the pay packet if you let the Engineers do Pilot duties.....just saying.

If the cab goes airborne, decides to enter Ground Resonance, or leaves a parked position firmly on the ground....who would you rather have sat at the helm...Engineer or Pilot?

[ShyTorque]

Engineer! :ok:

[Matari]

Wizzard, true story. PM me if you want all the details.

[I Build 92's]

In the old days here at Uncle Igor's, the aircraft crew chief used to perform the maintanence ground runs. We complied with the first run in the morning prior to release for test flights and any subsequent ground runs for maintanence performed, vibration adjustments or leak checks. You were required to pass a written exam and 10 starts with PIC to get signed off. I was authorized to turn S76A & B models and the UH-60A Blackhawks. While I sat left seat for many runs in the S61's, S-64's and even a RH-53D I never managed to get those on my run card! Only incident I recall was "Tail Spin Tommy" chasing a fire bottle with a Blackhawk and I had heard of 2 S58's meshing rotors unsuccesfully!! Maybe John Dixson remembers a few more.....
All was ended when the Navy decided it wasnt a good practice to let us boys play with their toys!! :=

[tracker69]

what comes to mind here is 2 things

1: When something happens what does the insurance say
2: How the Hell have the CAA not put a Stop to this

I think its wrong unless your ppl rated you should not be able to run anything

[EN48]

I feel with the correct training there is no reason why the engineers can not run the aircraft.


With the correct training, even a pilot can do it! :E

[ec155mech]

thats a bit narrow minded.
being an engineer myself and having permission to do rotors running ground run I find it extremely useful. and Im sure the pilots and the company appreciate not having to spend duty time on waiting around for us to do adjustments, leak checks ect. at all hours of the day.

we receive a start up course, get examined by the training captains on a regular basis. get quizzed on emergencies and procedures.

some of my coworkers have more experience in starting a helicopter let alone fly it than some of the company's FO's

so given the right training and procedures. I see absolutely no reason what so ever, that the local CAA's should put a stick in this.

if the insurance company is aware of this I do not foresee any issues.

Att SASless, thinking that engineers doing ground runs will impact the salery is IMO a bit paranoid. as we can still not do test flights. so I wouldnt worry.

[AnFI]

I think the UK CAA ANO does have a rule against it

(think it says something about being 'qualified' tho it doesn't say what that means)

[Troglodita]

Doesn't ICAO now define Helicopter Flight time as Rotor Start to Rotor Stop?

:}

Trog

[ShyTorque]

Doesn't it say "rotors started for the purpose of flight"?

[Pofman]

The relevant reference in Europe is JAR-Ops 3.210(d) which requires specific rules be layed down as to who may run the helicopter apart from qualified pilots. This is expanded in an AJC OPS 3.210(d). Normally once the rotors are turning the helicopter is capable of flight or toppling over. Therefore as a general rule we allow only qualified pilots but other personnel may be cleared under laid down provisos.

[Rigga]

AnFI,
"qualified" without giving a specified trade (pilot/eng) or standard (course/licence) means that local training to company satisfaction (company authorisation) is possible. = Company trained "personnel" could do it.

I am not saying the CAA/EASA would allow it - but it shows a bit of a hole in the rules.

[RVDT]

The recent AS350 accident in Brazil where the helicopter was destroyed on the ground by severe vibrations after landing brings to mind the perennial question of helicopter engine ground-runs being performed by engineers/mechanics.

Really? How does that "bring to mind the perennial question?"

I thought this aircraft had a pilot in it.

[Amatsu]

I thought EASA regs stated helicopter flight wast "Engine Start to Rotor Stop" and that a "helicopter must have a rated pilot on board at all times during flight".

Never understood how this worked with solo students though. Also I've noticed that a fully rated pilot will turn down the honor of ground running an aircraft if his LPC on type has expired stating that it is not legal - so how do us lowly mechs get away with it????

On the subject of engineers doing ground runs, I do know a guy who spun an R44 on the pad when he opened the throttle to quickly. Don't think he'll do it again though.

[Helinut]

There is more to this than the legal guff, but in the UK this may be relevant:

UK ANO

Article 256.—(1) An aircraft is deemed to be in flight—
(a) in the case of a piloted flying machine, from the moment when, after the embarkation of its crew for the purpose of taking off, it first moves under its own power, until the moment when it next comes to rest after landing;

[Another bit of the ANO says you have to have a pilot at the controls if you are in flight. By default then, if you are NOT in flight (as defined) anything goes].

So, if I understand it correctly, our leaders have decided that it is perfectly legal for a non-pilot to be in control of a rotors-running helicopter, so long as you do not plan to get airborne.

I recall some while ago, we were all told that we should never let a student start-up without us, following an accident on the pad.

As a piece of legislation trying (presumably) to control risks on a rational basis, it has more holes than the swiss cheese.

Am I right in thinking that an accident occurring during ground runs may not even be required to be reported as an accident, on the grounds that it did not happen during flight (as defined)? Just an engineering incident!

For me,(I think prompted by some pilot mentor in my past), if the rotors start to turn, I am flying it. Harness on, headset/radio on and ready for anything. The hazards start up as soon as the rotors turn: the rotor blades do not know what the intended purpose of the start is.

[before landing check list]

Really? How does that "bring to mind the perennial question?"

I thought this aircraft had a pilot in it.

RV, if the AS350 had operating RPM the pilot should have brought it to a hover. For some reason the pilot did not do this. It would have been a non event. If the RPM was low you have to ride it out.
We are assuming pilots can hover, mechanics cannot. However I have seen mechs who can hover better then me.

The "perennial" question; should mechs do full RPM run ups or not. I say overall no. It is too easy to get it airborne accidentally or otherwise. Ground idle only or at least tied down so hard ground resonance cannot occur.

[ShyTorque]

CAP 393 Section 1, part 8, page 2:

(5) For the purposes of this article, a helicopter is in flight from the moment the helicopter first moves under its own power for the purpose of taking off until the rotors are next stopped.

So strictly by the book, an engineer can legally start the aircraft from cold, but he can't take over "rotors running" then stop it after it's first moved under its own power....

[Peter3127]

Regardless of the rules (and I expect we all want to meet the "spirit" of them).... I would suggest it is incumbent on all of us to ensure the safety of those involved in any operation.

As a student I have been taught (in the 300CBi, and yes I know it looks like a chicken carcass) that while cooling the machine down at 2500 RPM the machine is at Flight Idle and demonstrably capable of flight. And it is, at those RPM/RRPM a good turbulent gust could flap the disk etc. and cause an issue if you are not on top of it. If you can autorotate at the equivalent RRPM, the machine, given the right angle of inflow, can sustain flight even with collective down.

Whether you are 1, 3 or 15 feet in the air at that point, who knows? But at that point you should know how to deal with it.

Begs the question among the instructors ..... who jumps out and lets the students do the shutdown on a windy day?

None of this is meant to suggest that an Engineer/LAME cannot do a ground run. Of course they can if trained and certified to do so. They are likely more capable than the student left sweating in the cockpit with the checklist in hand.

p.s. There WILL come a day when I no longer need an Instructor, as far away as that seems. I have yet to have a day though when I do not need an Engineer/LAME and can't imagine a week when I won't. :D

[TukTuk BoomBoom]

I think the Brazilian Astar is a special case. Having done a fair bit with AS350s i can tell you that they dont get ground resonance without some serious issues mechanically, landing gear dampers with no oil, skid springs flat and bearings shot in the AVA.
They certainy dont shake apart without having a few days of increasing divergent ground resonance that is either handled by the pilot or sorts itself out as the rpm changes on run up or pulling the throttle to idle.
Should have been dealt with way before it got to that point..

As for ground runs im with Robinson, pilots only unless the aircraft is secured to the ground (not for multi blade aircraft through, cant tie them down)

The other issue no ones mentioned is trying to get some lazy ass pilot to do ground runs because "theyre so busy".
Sometimes its quicker to do it yourself!

[mtoroshanga]

In the Air Force I was in the engineers fle with the helicopters at all times as well as carrying out servicing at base. They were also winch operators and primarily air gunners. On positioning fllights we flew for roughly half the flight generally and received instruction from our designated pilots.
I have been in aviation for fifty years now and have accumulated about 4000 hrs on everything from Alouettes to AS332s and including Bells and Sikorskys throughout the range.I object to doubts being cast on my abilities by the likes of SAS who I know and others.

[SASless]

I object to doubts being cast on my abilities by the likes of SAS who I know and others.

Did I mention you by name?

I do believe i suggested the "best" qualified individual be at the controls....and as even as much as I value all the experience and ability Engineers bring to the work place....there was no slight meant when I reported my choice for run-ups being a Pilot rather than an Engineer.

Now depending upon exactly which Engineer it might be.....I might in fact have some grave doubts as to their eligibility and competence to perform run-ups as there are some that I would rather not approach an aircraft for any reason much less to fire the puppy up for a ground run.

As I only suspect who you really are....in this case i can not state categorically which class of Engineer I would place you in.

I like the idea of Pilots and Engineers working together as an integral part of a team dedicated to maintaining the aircraft to the highest standard. Likewise, there is a great amount of knowledge that can be transferred both ways during such interaction that benefits both Pilot and Engineer. Unlike most ex-Military Pilots (particularly American), I do not see a "class" (rank) difference between Pilots and Engineers. I see both being parts of the same puzzle.

[RVDT]

before landing,

if the AS350 had operating RPM the pilot should have brought it to a hover

Show me that in "black and white" and I will agree with you. i.e. the statement in the approved RFM.

BTW if you check the RFM of most EC products under Minimum Flight Crew and the local NAA definition of "flight" you can only use a pilot. Unfortunately the statements are not uniform across models of the same type!

As Tuk Tuk sez - 350's do not decide to come apart as a matter of course. There is a mechanical problem.

[before landing check list]

RD, I have not flown a AS350 for quite awhile however I always was taught and I teach that if it has RPM to fly then bringing the machine to a hover is the remedy for ground resonance. Is this not so? I have no RFM in front of me, if you do what does it say?

[hillberg]

So some babys don't want mechanics to do run ups on helicopters and for the "government" to add more "rules" for so called safety?

3 questions.

1. how many idiot pilots you think should stay away from aircraft all together?

2. how many idiot mechanics you think should stay away from aircraft or even bicycles?

3. Looking at the track record of governments, You must ba an Idiot moron to ask for more regulations from any government that can't even ballance the frigging national budget.

Training & good communication is the answer. Not government.

[ShyTorque]

Hillberg, isn't that only two questions, plus a statement of opinion? :)

Which one is the post on this thread where someone asks for more government regulations? As if there weren't enough already....

[hillberg]

Caught it. :D Communication.:ok:

[Saint Jack]

Many thanks guys for the quality and helpfulness of your replies. It does appear that a significant majority of us are in favour of, or at least have nothing against, engineers/mechanics performing helicopter engine ground-runs - but with proper training and strict limits on what can and cannot be done - no objection there.

To Troglodita (#20) and Helinut (#26) I would say that your referred definitions are for 'flight time' which is used by pilots, i.e. flight and duty time limitations. Also, remember that apart from post engine wash drying runs, the helicopter is probably unserviceable (if an engineer/mechanic is running it) and therefore the question of 'flight' is not applicable. However, if you meant the amount of engine operating time for maintenance tracking purposes then this is calculated by using 'time-in-service' and is not applicable to ground operations.

EN48 (#17), nice one......

[TukTuk BoomBoom]

"Unlike most ex-Military Pilots (particularly American), I do not see a "class" (rank) difference between Pilots and Engineers. "

You making more friends Sasless?

[ecureilx]

Amatsu: am not a flyer or a fixer, but, out of curiosity, as you mention a case, if an engineer spins a helicopter, what happens to insurance coverage ?

[Fareastdriver]

The insurance company would be aware of the Operations Manual when they take on the risk. Engineers running helicopters after company training is part of that risk.

[Helinut]

Saint Jack,

I don't believe you are correct in your view about my quote of the regs, either about my intention or the conclusions to be drawn. I was just interested to remind myself what our UK regs said about the issue. They say that a rated pilot must always be at the controls "in flight", but the articles ShyTorque and I quoted make it clear that ground runs are explicitly NOT "in flight". The UK CAA has gone to some lengths to exclude ground runs from any requirement to have anyone with particular qualifications, training or experience at the controls. The regs permit a passing Tesco shelf-stacker or estate agent to do ground runs.

In my experience, where I have worked it has always been pilots who are asked to do ground runs. The engineers I have worked with have never shown any inclination to do them (unless they also were rated pilots). I have always welcomed the opportunity to get involved in maintenance activity, even if it means staying late. As a pilot and non-aero engineer I want to learn as much as I can about what I fly and the people who maintain the aircraft I fly. I think SASless has it right about it being a useful joint exercise.

However, in principle, there cannot be any good reason for restricting this role, so long as the person who does it has the training and experience to do it safely. In this litigious world, you better make sure that you have that training and competence written on tablets of stone. I suspect that is why, in my world, pilots are asked to do the ground runs.

Someone raised the idea that it must be possible for engineers to do ground runs, because the aircraft was under maintenance and therefore not available for flight. I am not sure that is a helpful boundary to draw: one does not follow from the other. Is anyone going to say that an engineer should fly a helicopter during tracking and balancing flights, because it is part of maintenance?

[Tynecastle]

When one large company became the world leader in SMS, they required 2 pilots to carry out the S61 drying runs, even non-engaged runs!!!!

[Saint Jack]

Helinut: My apologies if I misunderstood your post, as I'm sure you can understand, the problem with quoting regulations is that these and there interpretation can vary from one geographic location to another - sometimes quite significantly. But the general concensus does appear to suggest that engineers performing helicopter engine ground-runs is permitted athough as you say, some may be reluctant to do so.

[Fareastdriver]

I can recall two occasions where an aircraft had been damaged during ground runs. One was where the main rotor actuators had not been connected to the helicopter's roof and the other was when the pilot forgot to release the main rotor brake. It was dark at the time so he did not realise the rotor brake was overheating until the apron started getting obscured by smoke.
The first case defies belief but could have been avoided if the pilot had done a customary walk round. In the latter case with an engineer it would be unlikely to happen because all the engineers I know in the fixed wing world use a checklist.

Using a checklist, if only occassionly to keep yourself up to speed, would have avoided both situations.

[SASless]

Tukkkkkks....



You making more friends Sasless?


Just telling the truth....and if it steps on some Corns....then there we are.

The Brits and most other Military forces have Enlisted Pilots....The Americans do not.

Long serving American Military pilots sometimes find it hard to drop the Officer/Enlisted attitude once they shed their uniform and enter Civvie Life.

[Vertical Freedom]

F...n madness :ugh:

some machines can fly even at ground idle & if she starts to play up & wanna start to fly....oooooooow scary :eek: remember 'Hog' -'get away from that thing, after he wrote that H269 off & miraclualusly not himself

As the addidge goes; anyone with the correct amount of training can do it, including Pilot's. Hence if an Engineer is also PPL(H) or higher, then of course they should & can safely start that fling wing contraption :\

Happy Landings

VF

[ShyTorque]

The safest way is how the RAF engineers used to do Chinook ground runs (possibly still do).

They removed the rotor blades. :ok:

[before landing check list]

Long serving American Military pilots sometimes find it hard to drop the Officer/Enlisted attitude once they shed their uniform and enter Civvie Life

SAS I don't feel that this is overly true nor just limited to this side of the pond. As a retired CWO who attends many functions of retired mil types I can attest to this.

[Rigga]

ShyT:
"The safest way is how the RAF engineers used to do Chinook ground runs (possibly still do).

They removed the rotor blades."

The last time I called up a Blades-Off Ground Run (on a Mk1 at Gutersloh) it was done by a pilot (well, I think it was a pilot?) who became nervous when I pointed out 80 open Jobcards and a crewroom chair for him to sit on.

[Outwest]

When one large company became the world leader in SMS, they required 2 pilots to carry out the S61 drying runs, even non-engaged runs!!!!

That was changed in 2005......one pilot only. Engineers were approved to do rotors stopped engine drying runs as well, although on some bases the engineers refused to take the responsibility.

[mtoroshanga]

Just a couple of points on this subject.

Rotors turning time is no longer logged in any company I have been involved with,it is flight time only that is logged and to the minute now not to the nearest 5 asit used to be.
I have always been expected to respect duty hours, surely it is common sense to utilize engineers on site rather than to call pilots in so wasting duty
time.
We ceased doing ground runs a while ago because of insurance issues so its a bit academic.

[dpashton]

Insurance is the main reason ground runs are being done less by engineers. That being said, insurance companies are responding to things that have gone wrong during run ups. I have seen an engineer cook a turbine on a start, pound out the striker plates on an MD369 by starting with the cyclic off centered (hell of a racket), and I myself did a 180 degree spin running an AS350 on an icy pad (scared the s**t out of myself). Things can and do go sideways during a run. Granted training was an issue in all the fore mentioned incidents, however, the simple fact is, as engineers we just don't do it often enough. As a younger engineer I thought it was better not to bother the pilot for the run but now I am happy to bow to their experience. I would rather have someone at the controls who can respond in an emergency.

[riff_raff]

The safest way is how the RAF engineers used to do Chinook ground runs (possibly still do). They removed the rotor blades.You can remove the CH-47 blades........... or they might just remove themselves.:eek:

Ground Resonance - Rear View - YouTube

[SASless]

This was purely an Engineer induced catastrophe.....the poor ol' Chinook was to be shot up with various sizes of things that go Bang. The Engineers rigged up a remote engine control system....chained the old girl down so she could not escape....and the rest is history as they say.

[Fareastdriver]

People start panicing about rotor bladeless ground runs. The Puma series have an accessory drive function that is available if the customer wants it. It disconnects No 1 engine from the MRG but still enables it to run No1 Alternator and No 1 Hydraulics. Its a spin off from the Fred Karno attempts to have a self-propelled undercarriage.
I was asked to do a run on a 332 with the rotors removed as it was in storage and needed to be run. The engineers were concerned about rotor overspeed so I had a long briefing warning me about how fast the rotor would speed up without any blades on.
About twenty years previously I had done runs in accessory drive. The engineer was sitting beside me as I started the engine and it settled at ground idle.

When I slammed the governer lever into the flight gate his face was a absolute picture.

[Vertical Freedom]

Ha HAAAAA Fareastdriver, Man that's good, what classic http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/eek.gif hehehehe

I Love PPRuNE, hehehehe how would I pass the evenings without You; PPRuNe?? http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/sowee.gif

Thanks for the larf :D

I don't fly at night, so I PPRuNe the night away...... http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/confused.gif

Happy landings http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

VF http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/cool.gif

[ShyTorque]

Trouble with that accessory drive on the Puma was that it was known to disconnect in flight without actually being asked. I think you then lost the MGB oil pump drive.

As Fareastdriver will know, RAF Pumas had the facility removed around the end of the 1970s after a "few issues".

Shame about the hydraulically powered wheels really, as I'd have loved to put a set of off-road knobbly tyres on my Puma. Mind you, the sloping ground limits weren't so good. ;)

[Fareastdriver]

The reason it was discontinued was not because of a flight problem; it was finger trouble. For some reason a crew, 2 pilots, decided to to a disconnected drive run. They did this properly but when they re-engaged it they omitted to insert the locking pin which explained the noise just after startup. The pins were wire locked and later gearboxes did not incorporate the facility. Anybody who has an INTERNATIONAL 332 manual can see the levers on the left hand side of the thottle quadrant. On the aircraft they are the uncut blanks.

hydraulically powered wheels

It was actually a baby tank track either side so it could not retract. The nosewheel had a snow ski arrangment so it could cross ditches.
The test vehicle was a load of angle iron with a hydraulic pump and seat that that had the same footprint as the aircraft. When it set off in Marignarne there was a board in the hanger with times up to ten minutes on it. This was the sweep and when the inevitable bang and squealing came from the distance somebody would collect the money.