skippydiesel

David Clark HS - Needs new "Dome"/ear cup - ordered.

Cant believe how thin/flimsy the cup is where the mike boom is attached - like an egg shell only not so strong.

Need to come up with absolutely safe way of removing the silver/metal  retainers on wiring (see photo).

Suggestions, preferably from those with experince, welcome.😈

One of my two EGTs has become slower than the other to indicate (from cold)  and remains consistently lower, during all phases of operation.  Its not by much but is irritating.

Before you respond with advise about carburettor balance, exhaust blockage, electrical connection integrity, swopping leads/positions. etc - all of this has been checked/double checked - the difference remains.

It seems to me that the thermocouples are not equal in their reaction to EG temperature - one or both should be replaced.

If possible I would like to determine which EGT sensor is reading high or low - Anyone got a test for this?😈

I stand to be corrected:

I am sure I read an article, many many years ago, about this aircraft type being developed specifically for flying over the Amazon jungle. Open areas for forced or deliberate landing few & far between. They are purely for low level, warm climate, observation (wildlife?) patrols.😈

I hope its a fresh water sport - Can you imagine what salt spray will do to electrical connections/metal airframes.

AND

Think what a impact an, almost impossible to see, swell might have on this activity - scary!😈

I agree with this policy.

Its a shame that poor behaviour has led to this.

There was a time, long long ago, when passengers left the aircraft by the row/seat they were in,  AFTER the aircraft had come to a stop and the door opened. this was done without voluntarily, as a curtesy ie without instruction.

This boorish behaviour, that has become the norm, benefits no one, likly slows the departure process, certainly does not speed it😈

1 hour ago, Red said:

Whilst it's common for VRs to require the case to be grounded the Carmo makes no mention of doing this.

Also did you connect it direct to the battery with no fuse as the Carmo instructions indicate?

I am a big believer in good grounding for 12 V systems. Sure CARMO make no mention of the need however it cant do any harm & may help.

Connected to battery - through 25 amp fuse as per Rotax recommended practise. I only have one circuit not protected by either a fuse or a circuit breaker. The one is my external battery charge / jump/ supply port😈

Hi Danny,

Good idea to raise the VR off the mounting surface - just be sure that its making a very good earth contact.😈

"I was one of six Bathurst Soaring Club members in four aircraft (C182, Maule M4, Hornet Cub & Corby Starlet), who enjoyed an 808nm five day trip around NSW (& briefly VIC) last week.

........................................................

All together a most enjoyable trip. Both aviation Museums are well worth the visit and comprehensively detail the importance of these aerodromes / lake during WW2."

Next time you go on a airborne tour, perhaps you would promote it on this Forum, so that others may join in😈

1 hour ago, sfGnome said:

Is the cooling cap a Sonex thing or a Skippy thing? Where are you picking up the airflow that you’re feeding to it?

Bits & pieces from here & there.

Sonex are still new to Rotax installations, so no ideas from this direction

• The idea came from VR problems/solutions in RV12's
• The cap was made to order/design, by my Son on his 3D printer.
• The fresh air supply is through SCAT tube from a T piece, to the cooling cap, in the cabin left hand fresh air vent.

Down side with the above -  in winter there is a nasty draft from it onto my ankles. I have reduced this discomfort by putting a short piece of hose (a choke)  in the air duct (SCAT tube) thereby reducing the air flow. The choke will be removed for summer flying.

😈

The following would seem to be an attempt to revive the Sonex Forum: https://www.sonexpilots.org

2 hours ago, BurnieM said:

https://www.vectriqparts.com.au/product/rotax-voltage-regulator-carr5115/

 

Did the wiring take much time/effort ?

 

No the wiring is straight forward - just be sure that connections are good & tight. There is a excellent diagram + specifications on the web site.

NOTE: The CARMO has  (from memory) mounting holes at 65mm centres and the Rotax 92 mm.  You will need to drill an extra hole or make up an adapter as I did:

Black top, with spout, secured in place with safety wire, is part of the dedicated cooling system.

Rectangular aluminium tube (drilled for air flow) is the adapter .

Black wire, (TOP) with yellow connector is to ensure good negative contact - I also cleaned of the black paint around the mounting holes & used a smear of dialectic grease. 😈

CARMO CARR5005 MOSFET working like a charm.

14.5V - amps vary according to demand, from 12 down to 1 amp

Temperature up to 38C 

Happy pilot 😈

There is no way he could communicate effectively with that radio.

At those engine speeds he should consider a reduction drive of some sort.

Otherwise - very well done - must have been an exhilarating first flight😈

Well I got the new VR in today. Much bad language, some pain and not a little satisfaction. Will do the engine run tomorrow - fingers crossed😈

IBob - does Kyle Communications have your solution??😈

"The earlier Savannahs had fixed seating, fully back, so it wouldn't have been an issue."

Would not the KISS solution be to extend the length of the flap handle , commensurate with seat forward movement/position, rather than go to eclectic flaps, which introduce  issues best avoided?

"As for how much flaps: the Savannah is pretty much a STOL aircraft if you want it to be."

I have never flown a Savannah. Wikipedia has them with a 26 Knot stall. The ATEC Zephyr I flew, for about 10-12 years, had a sub 30 Knot stall (arguably also STOL). Having no experince, I can only speculate that the more flap you put on the more drag you introduce, which  can certainly assist in powered approach to a STOL/Short landing but the question is how much shorter will the landing be if you just used say 1 -2 stages of flap and came in with less power on or even a glide approach?😈

"Some have given intermittent failure at under 350 hours from experience."

Is this a statement about  Rotax parts failure in general or are you still on topic - VR failures?

What are the symptoms of a VR "intermittent " failure?

Premature VR failures have been a problem for Rotax 9's since the introduction of the engine. Several modifications later, they are still failing in significant numbers. The Rotax party line has always blamed the installer/user - too hot, too much vibration. The reality is that the Rotax/Ducati VR is not and has never been "up to scratch". Independent investigators highlight poor construction/quality control, as the likly cause of early failure in the current iteration. Failures can occur from under 100 hrs (Hobbs) to any time up to several hundred hour. Mine failed at 153 hrs.

Factory built aircraft. legally must use the Rotax/Ducati VR. Home builds can and do look to alternatives, which may prove more durable.

Check out just some of the correspondence on the Rotax Owners Forum & you will find that  the Rotax/Ducati VR problem goes back to the 1990's and continues to this day.😈

2 hours ago, Blueadventures said:

That’s right, and done with engine running, with safety care.  Will do him world of good to find the specs in Rotax manuals. Maintainers must be familiar with the different Rotax manuals, their use and info.

The whole point of a Forum like this is ASSISTANCE so that the wheel does not have to be reinvented every time a hurdle is encountered - I doubt you actually  know which Rotax Manual addresses my question.

Next time you seek assistance, I hope the answers are full and helpful ie not so arrogant 😈.

25 minutes ago, Underwood said:

What tests checks did you actually make? and what where the symptoms of you're apparent failed regulator?, It looks like you never said what lead you to this conclusion.

Symptom -Voltage dropped from 14.2 to 12 V and negative amps being delivered at engine start  - no improvement during run up.

My eldest Son, Electrical Engineer, CPL and occasional helper and way way more flexible than his old man, did the checks engine off & running - diagnoses' VR has failed.

Since last post have realised I do have some the VR out of aircraft checks on the the unit; https://pointsforpilots.blogspot.com/2012/12/testing-rotax-912914-generator-and.html

😈

 "Specs in Rotax manuals"

Fair enough BUT which one of the four manuals?😈

On 23/05/2025 at 1:21 AM, aviatorpl said:

Hello IBob, I would be very interested to have details of your 12 degree flap handle design as at 81 I too have a problem to pull full flaps. I was planning to fit electric ones but maybe your handle will solve my problem

I rarely if ever use FULL FLAP.

On my Sonex, FLAP 1 increase lift & drag, FLAP 2 & 3 just increase drag. So 1 & 2 for standard approach & landing. 3 is only used to increase descent rate and is usually taken off well  before flaring. My last aircraft ATEC Zephyr was much the same.

"I too have a problem to pull full flaps" - If this is a reflection of physical strength required, I speculate you are trying to put on flap at too higher air speed.😈

IF my in situ tests were correct the alternator is working - I am hoping there may be some continuity/resistance checks that can be done on the removed VR???😈

VR OUT!!!

Anyone know of tests that I can do on the VR to confirm in situ failure findings?????😈

Speculation:  - While iconic in appearance - Very expensive to run - relativly big engine/thirsty AvGas - fixed pitch prop,- draggy airframe/slow cruise.

One for the wealthy collector?????😈 

19 minutes ago, danny_galaga said:

Just for sh*ts and giggles, I'm going to temporarily install the capacitor on my set up. I have an MGL radio, which is not highly regarded around the hangar, and since it seems to be getting worse without anything else seemingly changing, I suspect it's a bit dodgy. But it can't hurt to put that capacitor in the circuit and see if the radio improves. Ill report back on the results. Could be a week or two.

I was thinking to do the same. My VR is difficult to access - leaving the Capacitor in place, just reduces the number of times I need to go there (assuming removing it would require another difficult job) 😈