Hi Ian (Williams),
What fuel flow rates did you see on the trip?
We regularly cruise >7000' and the engine does run well at alt. Interesting
experiences over the last month or so though. Rob and Col overhauled the carbs
and set the mixture back to baseline. It had been way too rich and incremental
leaning now has it pretty right. While over rich I was getting rough running
above 6000' which I initially put down to carby icing given the conditions on
the flight, and a subsequent one the next day.Subsequent flights gave the same
symptoms however so couldnt be icing. I could count the carby ice events on one
hand over the previous 12 or 13 years. Further leaning rectified that so as Rob
pointed out, an initial setting that's too rich prevents adequate altitude
compensation.
As an aside, Rob picked up fine cracks in the balance hose when he used 4x
magnification glasses during engine DI. I must have looked at it a dozen times
with my 2x and didnt pick them up so something to watch for.
Regards
Laurie Hoffman
From: Ian Williams <[email protected]>
To: [email protected]
Cc: 'Tony Noble' <[email protected]>; 'Conal Edwards' <[email protected]>;
'Jonathan Cross' <[email protected]>
Sent: Wednesday, 18 February 2015, 7:15
Subject: RE: [DOG mailing list] Dimona prop issue
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Ian, Thanks for that … I have taken the spinner off this morning andhad a good
look at the latch. I think the problem is that I maybe overdid thelubrication
of the centre shaft as the latching system has a lot of oil on it … just around
the latch plate. So I think the best option is to give the latch agood clean
off and try to keep any grease off it. It would figure because theengine has
around 50 hrs and this problem has just happened. It seems to be okwhen the
airspeed is higher though. I guess the counterweights put more load onthe latch
keeping it in. There is no evidence of any damage to the latch plateor the ring
it latches on so I will try getting rid of the oil / grease aroundit. The
blade rotation “play” is the same for each blade … can’t tell you theexact
amount but seems quite OK. A week or so ago I flew it direct from Drury (in
Auckland) toAshburton (about ½ way down the South Island. Took 5 hrs and
around 70L fuel)It went really well I have installed one of those MGL fuel
computers which isjust fantastic … able to calibrate the existing VDO fuel
sender and also has afuel flow sensor. It is real nice to know EXACTLY how
much fuel is available. That trip also included Pat and I going from Rangiora
to Greymouth … Rangioraon the east and Greymouth in the West…. Over the main
divide mountains …. I wasreally surprised as the little rocket climbed to 9000
feet both ways. In factthe engine seems to run really well above 7000 feet.
I have a couple of things I need to address … It tends to rollto the left
above 90 Kts … not too bad but enough to be annoying .. I have beenputting tabs
on the wings to improve that and secondly, one side cylinder head(the LH side
looking forward) runs significantly hotter than the other (exceptabove 7000’)
I think it is a mixture problem. Re Grant … I have known him for a long
time. He is probably oneof the most competent glider repair engineers I have
known. His background isas a fitter and turner but has been working on gliders
now for more than 10years or so. He has replaced numerous canopys and has
rebuilt a duo discusfrom the rear cockpit forward … to name just a few. He
also replaced all theaileron bearings in our Dimona … I made the holes but he
did the rest. He isa loss to his previous employers I think. However I
believe he would needsome support in the administration area. Hope that
helps Best regards Ian Williams
From: [email protected][mailto:[email protected]] On Behalf
Of Ian Mc Phee
Sent: Wednesday, 18 February 2015 12:14 a.m.
To: DOG LIST
Subject: Re: [DOG mailing list] Dimona prop issue Yep been there done that.
Where will I start? Our prop went to Eric in August and back mid September for
the 6yr 11monthservice. It came back and would change to coarse and stay there
half thetime. It then went to gulf late September and slowly got worse. After
a week at gulf reached stage it would almost continually return toclimb. It
got so bad I changed pitch to mid position so the pilotscould get home. We
have S2500 engine so no issues. Complained to Eric sent it down on Oct 9 and
there it was for 15 weeks asEric did not know what was wrong. I say again
15weeks. DennisStacey visited him as he took the prop out of the box. Others
visited onmy behalf. No joy. Conclusion was from Germany to fit an exchange
boss at $250 total was$480 on top of $4800 to "service the prop". Why that was
notdone in first place I will never know. When at burketown there were 4
motorgliders there and ours was just out ofservice & had more blade rotation
play than all the rest. It is back nowand zero play infact prop has never been
better. First time every time. How much blade rotation play do you have. Now
a LAME friend advised me with engines and props UNLESS you are doingcharter
there is no calendar service ONLY hours service. Thus I asked ourGFA Dennis
Stacey and he sent me a heap of notes and links confirming this. Sofrom what
Dennis tells me we can ignore the 6 yrs 11month service & revertto makers hours
requirements if not in charter. I go along with if it ain't broke why fix it.
I will never ever goback to Eric for service. I would rather send it to USA or
Germany butnot AUSTRALIA AIR PROP. Eric is a nice bloke BUT. What a saga.
That is why I have a falke with FIXED PITCH & no way wouldI consider a 2
position prop. So as you see I am not happy. GRRRRRRRR Ian Mc Phee
0428847642
(Ian what do you know of grant nelson from your area in NZ. Keepit clubhave
set him up a workshop at keepit to do repairs)
On 17/02/2015 8:04 PM, "Ian Williams" <[email protected]> wrote: Hiall,
Thelittle Dimona here in New Zealand has now just passed 50 hrs and going
realwell. However we have started having a problem with the prop which
theconsiderable collective experience of this forum may have had the same issue
Whichis …. Changing from fine to coarse pitch is OK (though does need
asignificant pull) however if the airspeed is low(ish) it will drop backinto
fine pitch. It is a bit random … I have just been to the SouthIsland in it
(about 12 hrs flying time) at higher airspeeds it didseem to stay in coarse
pitch. Any ideas??? Iwill take a look tomorrow… maybe a good clean of
the latch with WD40 then someoil may work. But I would be really interested
in anycomments. It is a standard Hoffman BT prop and has had the ADembodied
…. 50 hrs since overhaul by Eric. I have checked all the thingsobvious like
thrust plate run out, the thrust plate bearings etc all look assupposed to.
Bestregards IanWilliams DimonaZK-GCB
