Hi Bruce…. Does sound a bit dodgy the prop staying in coarse pitch after an in flight engine start… not possibleif the set up is correct. Maybe the latch needs some cleaning
The 7 year is the “life” before an overhaul by an accredited Hoffman shop… The data is all on their web site … SB’s and AD’s. It can be extended 12 mths further depending on condition by the servicing engineer if necessary There was an AD a few years ago which replaced the pitch change rods (6mm to 8mm) due to some breaking. One thing I have found that the operating / maintenance book does not provide a max run out of the pitch change driven plate. I checked with Hoffman… it is + and – 3 thou. The suspicion is that excessive run out could have influenced the rod breakages. I look after 3 Limbach powered aircraft with these props. When I started work on one, it had an unbelievable 80 thou run out. A bit mind blowing I thought. Little wonder the poor little rods let go Best regards Ian Williams New Zealand From: [email protected] Sent: Wednesday, 3 June 2020 7:49 a.m. To: [email protected]; [email protected]; [email protected]; [email protected] Subject: Re: [DOG mailing list] Low RPMs Hello All, Thanks for the feedback. Kurt, I use a GoPro Session 4 with a GoPro mount on the end of the wing. I have used it on the other gliders in my videos with no issues. Never lost a camera. Keep us posted on getting your Dimona flying. Ian and Ian, We installed a rebuilt Slick 4330 magneto. We timed it and it sounds and acts like the engine is running well. So I don't think it is a mag issue. The aircraft mechanic that has been assisting me used a handheld device to check the RPMs and we found the Tach was about 100RPMs low. On Saturdays flight I got around 2550 on the preflight and same until I took off. The most I saw after takeoff was 3000 RPMs at 55kts. I know I was in takeoff pitch when I took off. Going between takeoff and cruise pitch has been somewhat of an issue when we have been testing it. During Saturday's flight I did shut the engine down and when I restated it it was in cruise pitch. I don't remember that ever happening when I flew her before. These facts have me wondering if the issue is a prop pitch issue??? haven't heard about the 7 year maintenance “relife” is that something that needs to be done by a Hoffman service station? As mentioned in previous emails we did have to replace the fuel valve so I will test the fuel flow to both carburetors as suggested. I will also check the carburetor seal and will probably rebuild both. Will also check the plugs and compression. I will let you all know the results. Thanks, Bruce -----Original Message----- From: Ian Mc Phee <[email protected] <mailto:[email protected]> > To: DOG LIST <[email protected] <mailto:[email protected]> > Sent: Tue, Jun 2, 2020 1:36 am Subject: Re: [DOG mailing list] Low RPMs Very interesting your thoughts Ian Williams. I like using UMA tacho which uses same pick up on bottom of slick 4330 but it has internal adjust pot and I have adjusted for hour meter to click over at 1500rpm. Thus I can do a long warm up and no engine hours. Could do similar with vdo and an air switch I guess. I have dealt with 2 out if Air a long time h36 one coming from Italy. The Italian one had never had the in line fuel filter out from behind the rear baggage area replaced. The pop rivets were original with original paint. The filter was over half blocked with red gunk. The Italians do not write up log books with correct hours as they have to pay tax to government on hours flown. Naturally the Italian game there is to not pay taxes! The other I check the fuel flow and was way downto 25lit/hr so got owner to order a new hardi pump from Germany. I assumed I had the fault. Now it was still lucky to to be 25lit /hr rate. He TRUMA fuel tap had never been replaced ever. I turned it slightly and sat on lip and it improved flow to 30lit/hr. Got a new correct valve from Diamond and fuel flow was restored to 65lit/hr from electric pump. Ian McPhee +61 428847642 Box 657 Byron Bay NSW 2481 Australia On Tue, 2 Jun 2020, 08:10 Kurt Redinbaugh <[email protected] <mailto:[email protected]> > wrote: All I will have Dimona N13EB s/n 3660 flying soon after, coincidentally, a 12 year down time. I'm in Reno NV. My question is how did you mount the camera for the great video? Thanks and happy flying! kurt On Mon, Jun 1, 2020 at 8:14 AM Ian Williams <[email protected] <mailto:[email protected]> > wrote: Hi Bruce, Nice Video. We are just going into winter in New Zealand so not much flying at the moment. Re low RPM Are all compressions ok. Check tappets I set to 6thou inlet and 8 exhaust What do the spark plugs look like. The centre anode should be a slightly darkish brown and all plugs should look the same Check out the condition of the carb rubber diaphragms there may be a split one. Easily done by taking the top off the carb. Be careful putting it back together the diaphragm has a little key protrusion on it. Replacement “kits” for those carbs are still available I have had a magneto failure... caused by a failed condenser .. had a 20 year life of no action then broke down after around 120hrs. But that was a dramatic power loss. Presumably the mag has had its 2 year bench check and the timing was set up correctly Also presumably the prop has had its 7 year maintenance “relife”. If so maybe the pitch angle is too coarse. Just a few ideas. I would be interested in what u find We get around 2950 static 3200 at 55kts climb in fine pitch Cruise at 2800 to 2900. Coarse pitch and cruise speed around 90 to 95 kts Our Dimona is a early one with the original aileron push rod configuration so we do get some aileron upward deflection at cruise. Not a bad thing tho ... both ailerons deflect upwards around 15 to 20mm giving some reflex. Best regards Ian Williams ZK-GCB New Zealand Sent from my iPhone On 2/06/2020, at 1:23 AM, pattoninfl.aol.com <http://pattoninfl.aol.com/> via dog <[email protected] <mailto:[email protected]> > wrote: Hello All, We now have our Dimona flying again after her 12 year hiatus. Check out the video: https://youtu.be/kKg5CO4YZlw I was able to fly her but we are still getting limited RPMs. On ground I was barely getting the required 2700 RPMs. In flight the most I could get was 3000 RPMs. Due to this she had a much slow climb than experienced when I flew her 12 years ago. When I tried to fly her yesterday, which was a much hotter day, I could only get 2500 RPMs during preflight checklist so I didn't fly. Can you give me any suggestions that might be causing the loss of RPMs? Thanks, Bruce Patton N22TC
