RansMail # 035 September 2004

Graham has suggested I let all the members of our informal Group know about a Rans 'build book' error which caused some concern, before being cleared up.

It is a sequence of correspondence starting with his to Sport Air U.K.

"To: Sport Air UK <rans@btconnect.com>
Subject: Can you help please ?

David-Gordon
 As you are aware, I have been working on G-MWEP with Dave wood (PFA
inspector) and owner Ed Wallington. We have finished one wing replacing the
front spar and lift struts. The other wing we thought was ok but removed the
fabric for a quick check. We have found that the tip bow needs replacing. (
Ed is going to phone you today about that) . We also found that the wing had
at some time been trashed and rebuilt , we think you did not do this work as
there are no log book entries to cover it. The work appears to be ok except
that the spar doublers are different locations and lengths from the other
wing. We consulted the build book and the rebuilt wing conforms to the Rans
spec. The spars come from Rans with the doublers already installed so we
decided to measure all the wings we could find to see what was going on. We
have come to the conclusion that the Rans build book is incorrect , but we
need confirmation of this. The implications of the book being correct are
very serious as the entire fleet would have to be checked and possibly
altered. I will try to list the differences as simply as possible but you
may need to speak to me about this.
Front spar
Root------------------------- 2inch doubler    no problem here
Jury strut attach-------------24inch doubler called for--no doublers found
Lift strut attach--------------30inch doubler called for--12 inch doubler
found
Wing spar extension---------No spec -------------12inch found.
Rear spar
root---------------------9.5 inch called for-----none found
Jury strut attach---------24 inch called for-----none found
Lift strut attach----------30 inch called for-----12inch found
Wing spar extension------No spec--------------9.5 inch found.

As far as I can tell , all aircraft are the same apart from this one which
has been repaired. Please can you get Rans to advise on this one as our
inspector is getting quite excited.
Many thanks, Graham Smith.

Dear Graham, Thanks for the note, I will be going down to the a/c either tonight or tomorrow and will have a look etc. I looked up the build book meanwhile and my old 1990 issue agrees with your longer sleeve figures. Let's see what actually keeps it airborne !

.....................So far it's a puzzle to me. I took tape measure this afternoon and felt through the fabric along both wings, fore and aft spars, but couldn't detect any external thickening at the load areas mentioned. Nor did I feel any rivets that may have signified an internal sleeve location. Perhaps there was a difference between models with the heavier aerofoil lift struts with the single lower fus. fixing pin, though quite why that should be any reason, I don't know.

Mike

Sent: Monday, September 06, 2004 2:18 PM

Subject: Rans S4 wing spars.

Mike
Panic over on the spar inserts. Rans have admitted that all the build books have the wrong page inserted on the materials spec page. Might be worth letting the other group members know.
On the subject of drooping flaps- If your flaps droop too much you will get stick shake in the climb. The way to tell is full power with one stage of flap and then retract it and see the difference in vibration. I am constantly taking up the slack on my flaps.
On the subject of speeds- Try full flap and 35-40 mph and 4000 rpm. Do not take the power off until you are well into the flare. 4000 revs is the very minimum here so take care. Properly executed this will give you a ground roll of just a few yards.
Regards
Graham