All and Mike
Your fears are shared in my hanger as well. In that I am in the USA, I will
take my new stronger mass balance arm to my trusty welder and have a cable
attachment flange put on it. As you so wisely concluded, the cable
installation was not designed well. The idea is fine, but if a builder can
not do it well, it is a bad design. I installed the turnbuckles and feel
that fixed the design problem.
(another example is the fuel sight tube that runs under the floor mat and up
and over the top of the cockpit.) Here in the USA we don't built it that
way either.
Just my thought. Remember "I am an amateur"
Cliff Shaw
1041 Euclid ave.
Edmonds, WA 98020
425 776 5555
http://www.europaowners.org/WileE
----- Original Message -----
From: "MICHAEL PARKIN" <mikenjulie.parkin@btopenworld.com>
Subject: Re: Europa-List: Mod 70
> <mikenjulie.parkin@btopenworld.com>
>
> Jeremy,
>
> I have been away on business and so have not been around to join the
> discussion about MOD 70 but I have to say I am very unhappy about the Mod
> and its possible implications. I appreciate that being a non current
> engineer makes my opinion of little value to Europa 2004 or Francis
> Donaldson, but that never stopped me before.
>
> Firstly, the installation of the cables on the Mass Balance arm during the
> build struck me as very much hit or miss procedure at best. Page 20-2 of
> the
> builders manual- quote- " Make the cable as tight as possible before
> swaging
> the sleeve. This operation is almost certainly a two person job, holding
> the
> cable and swaging tool at the same time." When I came to that, it seemed
> to
> me that obtaining a reasonable cable tension and getting the the mass
> balance arm normal to the tailplane torque tube was almost mutually
> exclusive. It was for that reason that I installed a turnbuckle in each
> cable - this enabled precise measurement of the mass balance arm and
> allowed for a predictable tension to be set. I don't know how many
> builders
> adopted the same approach, but I know I am not alone with this idea.
>
> The requirement for a stronger mass balance arm was decided following the
> failure of one classic that had suffered ' a number of landing incidents'.
> OK, I can accept that without a problem.
>
> Last monday I drove up to Kirbymoorside to speak to Andy about the Mod and
> my misgivings about it. Andy has done a lot of testing on the setup and
> he
> showed me the new balance arm. It is made of thicker wall tubing and has
> a
> considerably more substantial adjuster assembly replacing the original
> TP18A
> adjuster. Andy also conducted some load tests on the original arm (in the
> vertical plane) he found that the test arm initialy twisted and then the
> lower tube buckled - he showed me the failed item. I am not sure whether
> the arm was installed in the aircraft, with cables attached, or whether it
> was just a straightforward bench test - if it was a bench test I doubt
> whether any cables were installed - perhaps if cables had been attached
> the
> inital twist prior to failure might have been delayed. However, the new
> arm
> is much stronger and should do the job nicely - but there are no cable
> attachment lugs.
>
> I asked Andy why he had discarded the cables? His reason was purely to
> make
> the installation easier for owners. I explained my turnbuckle
> arrangement.
> to which he replied that it was not a problem and Europa could easily put
> the cable attachment lugs on the new arm. Remember that the identified
> weakness is in the vertical plane of the mass balance arm not in the cable
> system. I asked if he would contact Francis Donaldson, but he said that
> he
> would be happy for me to do it - as the new arm would be fitted with the
> existing, proven engineering - it should require no flight testing. As it
> happens my aircraft is in the workshop for its' permit renewal so I
> removed
> the D panel and the fuselage access panels and had a good look around.
> The
> fitting of the turnbuckles to install the new balance arm would actually
> be
> quite easy. After carefully measuring and marking the cables so that the
> end of the turnbuckle can be fitted in the correct place, the cables can
> be
> cut as far forward as possible, that is just short of the cable lugs. Now
> if the fuselage access panel, on the right side by the tail is in the
> standard position, the cut end of the cables can be brought outside the
> fuselage and the turnbuckle end swaged in comfort. The other end of the
> turnbuckle can be fitted to the attachment lug on the arm using a standard
> fork fitting, cotter pin and split pin. The new arm is then installed
> onto
> the torque tube and with minimal time in the rear fuselage, the barrels of
> the turnbuckle are fitted, the arm is adjusted to the centre of the
> pushrod
> containment assembly, the tension set on the cables and finally locking
> wires fitted to the turnbuckles. It may be necessary to drill a little
> out
> of the mass balance weights to reset the balance.
> Now the point is that if some europas, because arranging the mass balance
> arm normal to the torque shaft is not a given, and the containment
> assemble
> was built around the already installed mass balance arm. It is quite
> likely
> that the resting place of the new uncabled arm is not going to be in the
> same place. This means that the pitch tube containment attachment
> brackets
> will have to be moved, and quite likely the fit of the ply around the
> pitch
> tube itself may need adjusting. How much time will be required down the
> black hole to do that!!! Using the existing cables would avoid all those
> problems. I asked Andy why he hadn't considered using turnbuckles, his
> comment - - "Well people might not have any turnbuckles."
>
> What worries me is that this big lump of steel is going to be free to move
> left and right at will, perhaps hundreds of times in an hour in opposition
> to the slightest yaw of the aircraft. How much could it move? I noted
> that
> a value of 4mm was mentioned on this forum. In fact, Para 5 of step 3 of
> the modification leaflet states - "The diameter of the mass balance
> weights
> is 50mm, and the nominal clearance is 2mm each side - check that the
> clearance achieved is between 1mm and 4mm each side". I interpret that to
> mean that the lateral movement of the arm could be 8 mm. Such a movement
> does not take into account the flexing of the plywood of the pitch
> containment assembly - not the sturdiest of structures. In real terms
> this
> new arrangement could have these not insignificant balance weights
> 'clonking' left and right by maybe 12mm. Is this movement likely to cause
> any fatigue problems at the attachment points on the torque shaft -
> perhaps
> one of the forum metallurgists could advise.
>
> I discussed this movement with Andy and he said that the weight moves even
> with the cables. If they are fitted in the manner described in the build
> manual I can see that there might be some movement. With properly
> tensioned
> cables, there is negligible movement.
>
> Actually, it is not outside the realms of possibility that a fracture of
> the original TP18A could be accellerated because of lateral movement
> caused
> by slack cables.
>
> The bottom line is that, the history of why the cables were originally
> fitted to the mass balance arm is irrelevant. Many Europas have done may
> thousands of hours flying with he current mass balance arm configuration
> without a problem. Now following the fracture of one TP18A on an aircraft
> that has suffered 1 or more landing incidents we are all to fit stronger
> mass balance arms. Changing the arm is the right thing to do. But I
> totally disagree that discarding the cables is the right thing to do. It
> is
> one aircraft modified and tested at the factory for a few hours against
> the
> experience of the whole fleet.
>
> I understand from Bob Harrison that since I spoke to Andy Draper he has
> been
> told by his boss that he cannot put the lugs on the new arms as he
> promised
> me. It seems that the only way we can incorporate this modified component
> is the way Europa 2004 say, because that is what they have worked out and
> tested. I smell commercial pressure here.
>
> I fear we are in danger of throwing the baby out with the bath water!!!!
>
> I have sent this email to the forum in the hope that someone can allay my
> fears about MOD 70 - perhaps it might generate some positive comment.
>
>
> regards,
>
> Mike Parkin (G-JULZ - hiding in the corner of the workshop with cables a
> quivering.)
>
>
> ----- Original Message -----
> From: "Jeremy Davey" <EuropaFlyer_3@msn.com>
> To: <europa-list@matronics.com>
> Subject: RE: Europa-List: Mod 70
>
>
>>
>> Fred,
>>
>> It wasn't stripped threads - the threaded portion sheared in two.
>>
>> Tim,
>>
>> I offered and you declined. OK, I'm 6' and 220lbs, but I still contend
>> you're being fussy! :-)
>>
>> Cheers,
>> Jeremy
>>
>> Jeremy Davey
>> Europa Monowheel 537M G-EZZA
>> Europa Club Vice-Chairman, Webmaster, PFA NC Representative
>> PFA EC Member
>> If you can keep your head when all about you are losing theirs, then it
>> is
>> possible you haven't grasped the severity of the situation.
>> Tail done
>> Standard XS wings with mods underway
>> CM installed in fuse (with airbrakes fittings)
>> 1390 build hours to date
>> Intended fit:
>> Rotax 914 turbo, Airmaster CS fully-feathering prop
>> Lots of lights, buttons, switches, gizmos, and alarms
>>
>>
>> -----Original Message-----
>> From: owner-europa-list-server@matronics.com
>> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Fred
>> Fillinger
>> To: europa-list@matronics.com
>> Subject: Re: Europa-List: Mod 70
>>
>>
>> "R.C.Harrison" <ptag.dev@tiscali.co.uk> wrote:
>>> ...
>>> I understand that the part that broke ( Having been previously under
>>> extraneous circumstances!) was actually the adjuster screw thread,
>>
>> I think I'm beginning to understand. There is considerable inertia in
>> the counterweight, and a few good whacks to the tail in occasional
>> hard landings would put the lower arm components in compression once
>> too often, stripping threads? The rebound may not help either. I
>> know this is amateur engineering, but perhaps the trigear doesn't
>> suffer as badly in ungraceful handling, because the force exerted on
>> the counterweight will be less abrupt. Hope so.
>>
>> Reg,
>> Fred F.
>>
>>
>>
>
>
>
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