Thanks Tom,I was thinking something along these lines. An issue between rudder and tailwheel interplay perhaps. I know of instances of steering/rudder cables being too tight that have caused Dimona operators over controlling problems during the ground run. The comment of the previous owner of Michael's aircraft and the faulty tailwheel repair seems to confirm the possibility.I'm no engineer though and Rob, Nigel, Macca and others would know best.I don't have the wide T/W experience that you have Michael, about 1000hrs in SuperCubs, a few in Pawnees, Callair and some several hundreds in TMGs. I've flown quite a few TMG types and I have to say that after something like 15 years of operating, our Dimona is an absolute delight both in the air and on the ground.The other owners and myself have taken off and landed in what on occasions were horrendous cross wind conditions and the Dimona has handled them all wonderfully despite not having differential braking.If possible i would strongly recommend that you fly in another H36 to see if there is any difference to yours. Just remind me where you are located pls.I don't believe asymmetric blade effect to be of any real consequence with the L2000 and doesn't appear to be noticeable with the L2400.Compared with the other aircraft that you have flown the Dimona certainly does need sensitive control input. Just a thought, but after your extensive experience with US clockwise rotating engines and even though you are aware of the difference, any chance that you may still be unconsciously applying right rudder during rotation? Also wondering if you have any gliding experience in FRP aircraft Michael with which you can compare the H36.Best Regards Laurie
On Wednesday, July 26, 2017, 12:17:05 PM GMT+10, <[email protected]> wrote: Dear all, My dimona S.n. 3506 had developed ovalized bolt holes on the tailwheel steering horn over time (circled green in attached drawing from H36 parts manual). Although I had previously adjusted the turnbuckles to align the rudder and tailwheel, a subsequent off center touchdown would misalign the rudder and wheel – resulting in a startling condition in which straight rudder input yielded a strong turning output, ground loop imminent. The cause of the problem became apparent when I held the rudder firmly while twisting the tailwheel – three degrees of play was then evident. Disassembly of the tailwheel drive horn revealed the wear on the horn tube where it is fixed to the tailwheel shaft with two M10 bolts. Repair was accomplished by slightly reaming the oval holes until roundness was restored, and then bushing the M10 bolts for a tight fit – no play even before tightening the bolts. I now include visual tailwheel\rudder alignment check as part of my positive control check before flight..even a little misalignment results in nasty directional behavior right after the wheels leave the ground and right after they touch down. Cheers, Tom Sent from Windows Mail From: Michael Stockhill Sent: Tuesday, July 25, 2017 8:40 PM To: [email protected], Laurie Hoffman Thanks Laurie and Ian. I've owned my Dimona 16 years. I have about a thousand hours in taildraggers up to a DC-3, owned a Cessna 180, and flew a dehavilland Beaver for a few seasons before moving onto other things. I have flown many different tailwheel types and must say that my Dimona's ground handling is the most sensitive (to the point of occasionally being seriously uncomfortable) of anything I recall having flown. (When I asked the previous owner about crossword handling, he said to just go someplace else.) There were at least a couple instances where I had PIO on the rudders during landing before I determined that the tailwheel fork had been repaired with zero degrees castor or rake. It was very squirrelly and easy to over control on the ground before I reworked the tailwheel fork. That made it much better, but it has always wanted to head for the weeds (to the right) as the tail comes up for takeoff. (Perhaps when the tailwheel leaves the surface.) Much of the time I attributed this to habitual taildragger habit patterns of using right rudder during takeoff to compensate for P factor and gyroscopic effects rather than left rudder on the Dimona. Inflight handling, trim, and rigging are fine, other than pretty heavy ailerons in powered cruise flight. Although the book suggests a three point takeoff, I have always raised the tail at thirty knots or so (I have never really noted that speed as it is only when the airplane is ready, so don't hold me to that number). Wings are level with no aileron input to cause adverse yaw, but there is a significant yaw excursion. I seem pretty much used to this now, but have been working with a friend so he can fly my bird. He was a Naval aviator--a Top Gun spin instructor in F-18s etc. After a few takeoffs threatening a visit with the weeds he said he's never flown anything before that he couldn't comfortably take off. I have offered to come up with a way of providing him with a cat shot! This doesn't seem normal. It is like there is quarter right rudder as the tailwheel leaves the ground, so we have lots of fun overcorrecting. I really want to revisit neutral rudder and tailwheel to see if there is any deflection, but last time I looked I couldn't see anything out of the ordinary. I will get into the service manual soon (after an engine repair on my PIK-20E, with is another eventful story) and look into rigging. So anyway, what do you folks experience? This is way more than P factor. It is always a challenge to stay anywhere near the runway centerline on takeoff roll. I tend to let it find a line it likes rather than risk overcontolling. None of this seems normal for an aircraft with a long tail arm, although the maingear seems quite a bit forward of most designs and configurations. Cheers, Michael On Jul 25, 2017 4:48 PM, "Laurie Hoffman via dog" <[email protected]> wrote: I get the impression that Michael experiences the aircraft pulling to the right on most/all of his take offs on rotation? Cross winds would explain only some of these. I can't recall ever noticing it Michael. Is it yawing only or is there some initial roll there too? If you simulate the low speed flight in the air does that reproduce it? Possibly a rigging or control deflection issue. Best Regards Laurie On Tuesday, July 25, 2017, 10:33:18 PM GMT+10, Ian Mc Phee <[email protected]> wrote: Yep RHS x winds are always an issue. Have a look at the bight of prop and upward going prop and downward going prop. Big difference Ian McPhee 0428847642 Box 657 Byron Bay NSW 2481 On 25 Jul 2017 10:03 am, "Michael Stockhill" <[email protected]> wrote: Have any Dimona operators found that their bird diverges to the right when rotating for takeoff? Mine consistently does that as the tailwheel lifts off. After 400 or so flights I think I am past adding right rudder for a prop that turns contrary to all the taildraggers I have flown. Michael Stockhill Polson MT On Jul 22, 2017 3:23 PM, "Laurie Hoffman via dog" <[email protected]> wrote: Rob you forgot to mention that on two of those occasions when we had prop work done, that there were other faults also.The blades looked like they had been refinished by someone who had never spray painted before. At least once there was an issue with seal installation with grease being sprayed everywhere on use.Laurie Sent from Yahoo7 Mail on Android On Sun, 23 Jul, 2017 at 6:16 am, Ian Williams<[email protected]> wrote: Hi Rob,Can you explain the difference in TBO between the BT and T blades ? I thought both were the same.Best regardsIan Williams Sent from my iPad On 22/07/2017, at 7:51 PM, Rob Thompson <[email protected]> wrote: I just heard that GFA has adopted the CASA rules on overhauling propellers. See http://services.casa.gov.a u/airworth/airwd/ADfiles/equip /prop/PROP-001.pdf This means that as soon as it is documented in the system there is no longer a calendar time for overhauls. Ian McPhee has been dealing with Prop Care (www.propcare.com.au) in Brisbane for Hoffman overhauls and hopefully they will be soon doing work on Hoffman props. We are continuing to have a nightmare run with Eric at Australian Air Props at Bankstown. 3 times in the past 2 years our prop has come back to us with problems. OnceWAY out of balance then next time set much too coarse and only pulling 2000 at full power. Then recently he sent it back to us with the counterweights set incorrectly and the rpm was fluctuating on run up and early take off roll. Add to that he charges a fortune because he knows that the only other option in Australia is to send the props to Germany. Up near $4000 now for about 10-15 hours work. Fingers crossed that the Brisbane mob will be able to do them. Rob Thompson0429 493 828 From: [email protected] <[email protected]> on behalf of Michael Stockhill <[email protected]> Sent: Monday, 17 July 2017 4:23 AM To: [email protected]; Laurie Hoffman Subject: Re: [DOG mailing list] H36 Ignition Switch (and brakes) For what it is worth, the mag switches on my Aztec with similar magnetos are rated at 6 amps 125V a.c./dc. The p lead grounds the primary coil. I found one source that says the primary coil puts out about 150 volts. The secondary coil puts out 10-15000 Volts. 40 amp or even 20 amp rated switch looks like overkill for whatever reason. Maybe consevative because we only get one of them. Michael On Jul 15, 2017 1:29 AM, "Laurie Hoffman via dog" <[email protected]> wrote: Hi Tom and Mike, Rob and I have the wreck of an H36 from which we have salvaged many parts for our functioning H36, especially the L2400 which we had top overhauled. Tom, I gritted my teeth and dived back into the wreck to recover the ignition switch and a panel switch. The wreck is already well dismantled however I still had a cow of a job getting access to the switches and removing these. I dread to think how much time it would take to install a new switch in the original position in a complete panel. My strong recommendation is that if you have an ignition switch failure seriously consider installing a new switch in another location on the panel, simply reroute the wiring from the old to the new and then cover up the old switch and placard the new. Although psychically the switch toggles and bodies appear the same, the switches have a very different rating. The panel switch is rated 15A while the ignition switch is rated 40A! The link that you posted to a new switch I just noticed is only rated 20A. Maybe something like this one Tom.... Longacre 45423 40 Amp Weatherproof Toggle switch #1731 | eBay | | | | $ 22.95 | | | | | | | Longacre 45423 40 Amp Weatherproof Toggle switch #1731 | eBay Longacre 45423 40 Amp Weatherproof Toggle switch #1731 in | eBay! | | | | In Oz I have found Narva (driving light manufacturers) switches which look suitable. Heavy duty and this one rated at 50A for 12v. Heavy Duty - Products - Narva | | | Heavy Duty - Products - Narva | | | The wreck is a Mk2 by the way while our operational H36 is a Mk1 so if anyone needs a good Mk2 wing or two, let us know! Re hydraulic fluid, we use only OM16 which I gather is equivalent to 5606. Best Regards Laurie From: Michael Stockhill <[email protected]> To: [email protected] Sent: Saturday, 15 July 2017, 10:13 Subject: Re: [DOG mailing list] H36 Ignition Switch (and brakes) Hi Tom et al I think I found that the MS O rings are okay. Mine were fine through two rebuilds (preventative maintenance each time I put on new tires) over 16 years. Mike On Jul 14, 2017 10:01 AM, "Tom Preisser" <[email protected]> wrote: Hi Laurie, I have what I believe to be an ignition switch in my spares. Can't be positive without digging behind the panel to look at my installed switch, but you can check your removed switch against it. The spec is MS 35058-22 http://www.bandc.aero/ toggleswitch-MS35058-22.aspx And I think it could be a different spec to the other fuel pump, etc switches (beefier), given that it has a separate entry than the 15A switches in the old H36 parts manual (with part numbers no longer valid for Diamond)... BTW on brakes (and thanks Mike for your advice)... just now installing a new caliper piston which makes the O ring fit much better in the cylinder (seems I had to take off too much corroded material from the groove of the original installed one, so it no longer sealed tightly)... For those of you running DOT3 fluid, I have obtained some EPDM O-rings to use rather than the BNR (nitrile) MS-28775-218 O-rings supplied to me by Diamond (which they may have sent probably because the HK36 and DA20 use 5606 aviation brake fluid). See this RAS thread for the details on why BNR is not suitable for DOT3...https://groups.google.com/ forum/#!topic/rec.aviation. soaring/4MiwHrkryFg And I talked to a lady who has worked at Cleveland Brakes for decades, and she gasped!! when I said that Hoffmann used DOT3. She says Cleveland only recommends aviation brake fluid - but I'm sticking with DOT3 as per the US type certificate! Cheers, Tom On Thu, Jul 13, 2017 at 7:26 PM, Laurie Hoffman via dog <[email protected]> wrote: Hi All, After extensive investigation into intermittent electrical problems eventually developing into a situation where the motor had to be shut down in flight due to rough running, it appears that the culprit is the ignition switch. Physically, the switch appears identical to the other original panel toggle switches operating fuel pump, avionics, strobe etc. Does anyone know if they are the same switch and also is there anyone out there in DOG land who might have specs for the switches? Best Regards Laurie From: Greg Wilson <[email protected]> To: [email protected] Sent: Sunday, 18 June 2017, 8:10 Subject: [DOG mailing list] Easy fit ADSB These are a very easy install and cheap too. https://www.recreationalflying .com/threads/wow-these-are-goo d-looking-gadjets.161803/ Greg Wilson ------------------------------ ------------------------------ --------- You are subscribed to the Dimona Owners Group mailing list. To unsubscribe, send email to: dog-unsubscribe@lists. riverland.net.au --------------------------------------------------------------------- You are subscribed to the Dimona Owners Group mailing list. To unsubscribe, send email to: [email protected]
