Note the 'spanner' scratch that appears to have initiated the crack on the
s'bd-side arm.
Glad that EA4 are now awake!
Duncan McF.
----- Original Message -----
From: "Roger Bull" <roger@middlecave.plus.com>
Sent: Friday, January 19, 2007 8:41 PM
Subject: RE: Europa-List: Mod 72 question
> O.K. Bob, you woke me up!
>
>
> Rob Housman's answer is on the ball. Using Redux would necessitate
> increasing the clearance between the original tube and the new inserts.
> The
> Redux would not be strong enough to withstand the bending load, which is
> the
> critical part of the overall stress. The insert is intended to be a close
> but not interference fit in the outer tubes after reaming. Any small
> clearance which may exist after fitting the new tubes will be taken up by
> deflection caused by the initial load applied by the weight of the engine
> and propeller.
>
> The bending load is applied both by the vertical load from the weight of
> the
> engine acting some 2.5" approx forward of the weld affected area, and also
> by the small tube which is about 1" above the main horizontal tube. The
> forward thrust from the propeller creates this bending load. To that has
> to
> be added on one side the torque reaction. (Distances are from memory as I
> am
> writing this fom home).
>
> I have made a small change to the Mod leaflet to make the applicability
> criteria a little clearer. The factors which affect applicability are
> engine and propeller weights and c's of g forward of the undercarriage
> mounting frame, and the engine torque.
>
> Briefly all Rotax engined Europas, except those with classic engine
> installations and light propellers as defined in the Mod leaflet, will
> need
> to incorporate the Mod. So all Rotax engined XS models, regardless of
> whether 912, 912S or 914, and regardless of propeller will need the Mod.
> Europas with engines other than Rotax will need to be checked on a case by
> case basis. We have already established that Europas with the Jabiru 3300
> engine will need the Mod.
>
> It was orginally intended that the news of the Mod would be promulgated by
> the PFA and EA4 on their respective websites simultaneously -
> unfortunately
> that did not happen. The PFA have now updated their Type Acceptance Data
> Sheet to include Mod 72.
>
> We realise that quite a long time has elapsed since the failure took place
> that gave rise to this Mod. It was necessary first to establish that the
> failure was not a one-off due to a unique set of circumstances; research
> into the original calculations established that there was a more general
> problem. The we had to devise a satisfactory solution that would be
> reasonably straightforward to incorporate, then carry out tests to prove
> the
> fix. Then the method had to be agreed with the PFA, and the Mod leaflet
> written. This latter exercise proved rather drawn out, and several drafts
> were needed before the current version was agreed. Establishing why the
> original error in stressing was made during the reign of EMIL proved
> almost
> impossible, as the engineer concerned died a few years ago.
>
> I realise that many people may feel that an unnecessary fuss is being made
> about this Mod, but a look at the attached photo of the first, but not
> only,
> failure should prove interesting.
>
> Best regards,
>
> Roger Bull
> EA4
>
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com]On Behalf Of Robert
> Borger
> Sent: 19 January 2007 1:48 pm
> To: europa-list@matronics.com
> Subject: Europa-List: Mod 72 question
>
>
> Fellow Europaphiles,
>
> The Mod 72 topic has become too quiet. I've decided to give it a poke and
> see if I can wake it up again.
>
> I have all the various bits for Mod 72 on order. Etching primer, ACF-50,
> 16.5 mm hand reamer & Mod 72 kit.
>
> I am wondering why the heavy wall tubing is not bonded in place with
> something like Redux.
>
> Is the press fit good enough to support the frame?
>
> Would it be better to Redux the insert in place? Better support and
> corrosion protection?
>
> If not, why not?
>
> Good building and great flying,
> Bob Borger
> Standing by, wearing my nomex undies, ready for the flames.
>
> P.S.
> The reamer will be available for loan to any Europa builder in the U.S. or
> Canada who needs it for Mod 72.
>
>
>
|