Marty d's CH-701 build log

At least you can drive from one end of your state to the other in a few hours.

Well, I drove up to the other end of the state on Monday and bought an engine!

Thanks HITC for putting me on to Peter.  

The engine is 2000 hour ex-training plane (Foxbat).  Came with brand new muffler & pipey bits, brand new oil tank, and a hell of a lot of advice - most of which I can't remember.  (I did write down everything I could when I got home!)

Now I have no excuse - I need to get on to building the mount!

No excuse now except getting bent over paying the exhorbadent costs from Floods for the bearings and seal kits. I picked up my engine for the S21 almost 2 weeks ago now. Still waiting on the big bore kit to arrive.

I am not sure if I mentioned it to you before but your gearbox will need a overhaul as well so be aware of that. Usually the schools with get that done at 1000 hours but of course the engine is now another 1000 hours older so the gearbox needs to be done again because the school doesnt get it done at the end of engine life

Thanks HITC for putting me on to Peter.  

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I am not sure if I mentioned it to you before but your gearbox will need a overhaul as well so be aware of that. Usually the schools with get that done at 1000 hours but of course the engine is now another 1000 hours older so the gearbox needs to be done again because the school doesnt get it done at the end of engine life

The 'Peter' referred to is Peter Reed, formerly of the Skyflyte flying school at Kooralbyn, Qld. I've known him for 33yrs and worked several years with him as an instructor at Skyflyte, and I can safely attest that he is one of the very most diligent engine and airframe maintainers I have ever come across. When Marty said he was looking for an engine I knew Peter had one coming up for replacement so I called Peter and asked him about it. As has been the case in the past for as long as I can remember, Peter has been having the oil spectrum analysed at each oil change to detect any abnormal changes to component wear rates and he has been fastidious about the gearbox maintenance - and also running the engine on premium unleaded mogas. 

If my memory serves me correctly, Peter was one of the first, many years ago and well before this engine, to report the effects to the gearbox clutches, of using Avgas. Consequently he has avidly avoided the use of avgas whenever possible, and on the odd occasions where he has not had an option, he always flushed the engine at the first opportunity and refilled with new oil.

In the USA there have been countless reports of well maintained 912s running faultlessly to TBO in excess of 3000hrs in non-commercial operations, and several cases of them even exceeding 4000hrs.

Naturally I can't offer any absolute guarantees, but I will say that I would not have any hesitation in using one of Peter's ex-school engines, and just keeping an eye on suspended elements in the oil, oil consumption rate, and compressions of course.

I will also mention, as Marty did, that Peter is one of the most generous public-spirited people you are likely to meet, freely giving his time and absolute wealth of hard-earned knowledge, (of both planes and flying - he'd have well over 10,000hrs by now, most of it instructing), to anyone who asks.

How is "Power off Pete"

There is another one of these fabulous engines with exelent history for sale in the classifieds.  

How is "Power off Pete"

All of what HITC says is true (and by the way, he had some very nice things to say about your engineering skills HITC - from the pictures of your Doomaw build I reckon he's right!)

I spent a couple of hours with Peter and Gill at their place in Railton - 90 acres with a strip at the top of a ridge.  Peter flies to work which would be a lovely way to commute!  He gave me heaps of info and I could tell by the way he talked about Rotaxes that he's got a deep reservoir of knowledge.  

We discussed flying over the Strait, which he apparently does on occasion.  I asked him if he went over the islands (King or Flinders) - his response was "Nah - straight over!"  He said that the islands quite often attract some weather, whereas if you pick your time (early morning) and have a good chat to BoM about the weather on both sides, you can usually go straight over with no problems.  (He also showed me the very sensible PFD with attached 1-person inflatable raft that sits on his lap - designed for Bass Strait!)

I only wish we lived a bit closer, as I'd like to do my ticket with him.  Devonport is about 3.5 hours drive away from me - standard commute for you mainlanders but a very long way for Tasmanians!  Still, maybe I should camp up the north for a couple of weeks in the caravan and do a block of training with him.  I know it's hugely important to get a good instructor.

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I only wish we lived a bit closer, as I'd like to do my ticket with him.  Devonport is about 3.5 hours drive away from me - standard commute for you mainlanders but a very long way for Tasmanians!  Still, maybe I should camp up the north for a couple of weeks in the caravan and do a block of training with him.  I know it's hugely important to get a good instructor.

And there's only one other instructor I know who is even remotely in the same class as Peter. He has so many years of experience and yet never seems to tire of teaching, as so many do. And that's often the problem - the new/young instructors are often full of enthusiasm and goodwill but don't have the depth of knowledge, varied experience or the skills to pass on, and unfortunately by the time they become 'old hands' they are often weary of instructing and become unenthusiastic, impatient and lazy. There are many exceptions, of course, but Peter is one of the bright stars in the sky (and on the ground in the classroom).

If I was you I would definitely use your caravan, choose a few days' window of good weather and do some block training at Peter's school, you won't regret it. You'll learn all the basics of course, but also those invaluable skills of finesse and survival under pressure. 

Ok it's been a while but I haven't been totally idle...

Getting into the controls and that's fairly exciting. As per another thread, I've heard it's better to "divorce" the elevator bellcrank from the flaperon torque tube. (For those who aren't familiar with the 701 design, the flaperon torque tube has a couple of welded brackets on top, and the elevator bellcrank sits on a small tube welded to them. Held on with a split pin if memory serves. This means when the aircraft is in a bank the elevator bellcrank is rotated from the vertical too, which can lead to the cables slackening.)

So I've gone the route shown in some Savannah plans and constructed a triangular bracket system that is attached at the back of the seat, the main gear channel and the torque tube support channel. This has made it quite solid which I'm pleased with.

Riveted to the side pieces are small squares of chrome moly, with hole drilled to take AN5 sized bolt. (Have to source an AN5-46 with drilled thread and a castle nut to go from one side to t'other). The bolt goes through a fitted tube which the bellcrank rotates on. Bellcrank is held in position laterally by pieces of a larger tube.

All this sits over the torque tube and the bellcrank swings close to it but far enough away to prevent any interaction.

Attached are some photos - the bellcrank tube is temporarily held in place by a couple of smaller AN5 bolts pushed in the end until I can get the long one. If anyone can think of potential problems or improvements to the setup, I'd love to hear from you.

Marty, the pull of the cables will be towards the tail (obviously!) So the cables are trying to pull the pyramid back through the torque tube support.

Is the bottom of your pyramid anchored to both the gear channel and the torque tube support in such a way as to avoid flexing of the torque tube support?

Hi Bob,

Yes, I think you can see in the photos, the pyramid is held by 6 rivets at the gear channel (flange is integral to the sides, all bent out of one piece each) and another 6 at the top of the gear channel. Plus 4 on the seat back, 2 of which are through the L angle at the seat back.

It feels really strong. I reefed on it as hard as I could and it just rocks the whole plane. I can't imagine there'd be that strong a pull from the cables.

Thanks for raising that though, I might put another 4 rivets on each axle end support and maybe an additional L run longitudinally under it to strengthen it in tension.

Quick update - having used Sketchup to design the engine mount in 3D, I used a program extension to "unroll and flatten" the various tubes needed and that gave me printed templates of all the bits.

They went together with only minor grinding & filing to get the fit right - can't say enough about 3D CAD, I couldn't have done the mount without it.

I use Autodesk Fusion 360 for everything. It can doo all of that stuff and then spit out the Gcode or unwrap sheet metal etc. Its free as well

We have started making the cabin frames for ours as well. Luckily we do have the engine mounts

On Wednesday last week my fantastic welder finished my engine mount, Y-stick and flaperon torque tube.  (The Y-stick was off a crashed Sav but not long enough - I got him to butt-join another length to it and also weld on the side pieces which bolt to the torque tube.)

The mount fits but needs some minor filing to clear the floor stiffeners, and the centre holes in the cups also need to be drilled out further, when I get a step drill that works.

I also want to prime and paint it before bolting it on.  Have started to make the brackets to hold the oil reservoir behind the mount - not a lot of room but it will fit.

I bought some rod ends and 5/16" threaded rod a couple of weeks back and have installed the linkages from the noseleg to the rudder pedals.

Also made up a protractor to measure the rudder throws, set the maximum travel to 23 degrees each side and installed the stops.

Will grab some photos next time I'm down the shed, but for starters...

Looks good, Marty. Where are the rudder stops on the 701? (I don't think the Sav has any...)

Looks good, Marty. Where are the rudder stops on the 701? (I don't think the Sav has any...)

 

Thanks Bob.  They're just a couple of 0.040" plates riveted to the bottom longerons and extending rearward til they hit the rudder horn when it's at 23 degrees.

On Wednesday last week my fantastic welder finished my engine mount, Y-stick and flaperon torque tube.  (The Y-stick was off a crashed Sav but not long enough - I got him to butt-join another length to it and also weld on the side pieces which bolt to the torque tube.)

 

The mount fits but needs some minor filing to clear the floor stiffeners, and the centre holes in the cups also need to be drilled out further, when I get a step drill that works.

 

I also want to prime and paint it before bolting it on.  Have started to make the brackets to hold the oil reservoir behind the mount - not a lot of room but it will fit.

 

I bought some rod ends and 5/16" threaded rod a couple of weeks back and have installed the linkages from the noseleg to the rudder pedals.

 

Also made up a protractor to measure the rudder throws, set the maximum travel to 23 degrees each side and installed the stops.

 

Will grab some photos next time I'm down the shed, but for starters...

 

[ATTACH]40614[/ATTACH] [ATTACH]40615[/ATTACH] [ATTACH]40616[/ATTACH]

 

It might be better to use an adjustable reamer to open up the holes. I've got a 5/16"" or 3/8" one (will need to check) that I used for fitting my carry through strut modification on my old Skyfox I could post down on loan if that's the size your chasing. Or can be purchased from engineering tool shops. Let's you get the perfect fit. Cheers

It might be better to use an adjustable reamer to open up the holes. I've got a 5/16"" or 3/8" one (will need to check) that I used for fitting my carry through strut modification on my old Skyfox I could post down on loan if that's the size your chasing. Or can be purchased from engineering tool shops. Let's you get the perfect fit. Cheers

 

Thanks for the offer.

I reckon it should be ok, they don't have to be any particular size - just bigger holes.  It only needs a thin ring of metal for the rubber mounts (which are compressed outward anyway by the bolt tightening and pulling the end washers in).  The big hole is so there's plenty of room for the metal tube the bolt goes thru inside the rubber mounts.

See a mount for a 601 below - compare the hole size to what I've got now.

Spent the last few days painting the engine mount (in what turned out to be a slightly greenish tint of yellow... guess it'll be under the hood so it doesn't matter!)

Today I got out in the shed and installed the oil can mount and finally the oil can itself.  Fairly tight fit behind the mount but it doesn't touch anything.

Did you find the rubber mounts?  I can find out where to get them from but they are not cheap. I can show you what the Sav ones are like as I just got my engine mount power coated so have easy access to the rubbers for a picture..they are funky too then sort of fit inside each other with the metal tube through the middle of the front ones

Hi Mark,  

I'm planning to use these - https://www.aircraftspruce.com/catalog/eppages/lycbushing.php?clickkey=3813

Just a shorter tube inset inside them with AN7-37 bolts going through everything.  Just have to source some 1" diameter cup washers for either end (car suspension parts looking good for that), or failing that just some large flat ones.

But yes any information is good so would love to see a pic of your setup!  Thanks.

When I get home later today I will take some pics...they sort of look like those on Spruce but not anywhere near as much taper

Mate of mine building a 750 used Polyurethane 40mm stock with large flat washers on the ends.  It looks good, but I'd be worried about whether it'd work as well as "traditional" rubber mounts.  He hasn't yet done any engine runs so guess he'll find out.

 I did the last engine mounts I worked on in Matt white etch.  Better to see any cracks with. Nev

Hi Marty

here are the ones supplied for the rotax in the Savannah engine mount