Canada Savannah

[dan tonner]

I have recently finished assembly and registration of my Savannah VGXL. During a rather high-speed taxi trial, I became airborn, panicked and managed a couple of hard porpoise bounces before finally coming to rest in a rough patch next to the runway. Did you ever see a grown man cry over a broken toy?

 

I bent the main gear spring - the top bend on the left side is "splayed" about 6 degrees and there is a downward "sag" in the top bar under the fuselage on the left side.

 

I am looking for advice regarding whether this level of overstress can be straightened while maintaining enough strength and flex for safe flight afterwards. If so, can this straightening be accomplished through cold bends without trying to anneal and re-temper the aluminum spring?

 

The front gear leg folded under resulting in more damage than just a bent mainspring, but the engine and gearbox have been checked out and were unscathed (god bless the slipper clutch) and the firewall, wings, fuselage and empennage were all untouched. Cowling repairs (and a new prop) are in process.

 

Your views will be appreciated.

 

Best regards,

 

Dan

 

 

[rankamateur]

It will explode in the press before you get it straight if it is that badly bent. They still make them, get yourself a new one. Have you ever seen this page before http://www.aerokits.net.au/prod04.htm , the first batch of them were fabricated out of the remains of the spring Reg tried to straighten, he keeps main gear springs in stock in Australia so your parts distributor probrably does the same.

 

 

[Kyle Communications]

Hi Dan

 

Sorry to hear about the slip-up. The aircraft flys at the drop of a hat as you found out. I flew into Maryborough airport a month or so ago to catch up with a lot of RC model turbine aircraft flyers I had not seen for a while. When I took off later in the afternoon the wind had changed and was blowing about 15 knots straight down the runway I taxied out and from a standing start gave her full throttle and literally was i the air after 10 or 15 metres climbing out with great authority at 60 knots. There was about 100 modellers there and all I could feel was my vibrator going off in my phone with sms 's from my friends just not believing that a all metal aircraft ultralight could do such a takeoff with such ease...and I was not on full flap only first stage (I have only ever used full flap twice and that was just to test it out). When you get her all repaired you will now be a lot wiser or if you are concerned please get a experienced pilot to take her up and do any trimming required. That way you are not concerned that that there are any things that will catch you out. it is no shame at all to get someone else to fly the first flight. I got my instructor to test fly mine the first flight as I just felt I did not have enough experience and confidence at the time to do it. It was the best thing I could have done because when he taxied in and got out and told me everything then I jumped in and went out and flew her...I was just tickled pink abeit a little nervous of course but that goes after the first 30 mins then its all good. Please get someone else to do the test flight then that will boost your confidence.

 

Mark

 

 

[dan tonner]

Hi DanSorry to hear about the slip-up. The aircraft flys at the drop of a hat as you found out. I flew into Maryborough airport a month or so ago to catch up with a lot of RC model turbine aircraft flyers I had not seen for a while. When I took off later in the afternoon the wind had changed and was blowing about 15 knots straight down the runway I taxied out and from a standing start gave her full throttle and literally was i the air after 10 or 15 metres climbing out with great authority at 60 knots. There was about 100 modellers there and all I could feel was my vibrator going off in my phone with sms 's from my friends just not believing that a all metal aircraft ultralight could do such a takeoff with such ease...and I was not on full flap only first stage (I have only ever used full flap twice and that was just to test it out). When you get her all repaired you will now be a lot wiser or if you are concerned please get a experienced pilot to take her up and do any trimming required. That way you are not concerned that that there are any things that will catch you out. it is no shame at all to get someone else to fly the first flight. I got my instructor to test fly mine the first flight as I just felt I did not have enough experience and confidence at the time to do it. It was the best thing I could have done because when he taxied in and got out and told me everything then I jumped in and went out and flew her...I was just tickled pink abeit a little nervous of course but that goes after the first 30 mins then its all good. Please get someone else to do the test flight then that will boost your confidence.

 

Mark

Thanks for the reply Mark;

I had already arranged the first flight to be handled by my Ultralight instructor...I think he was as excited as I was about getting my plane in the air the first time - he'd been watching the construction process, more or less, from the outset in 2011.

 

It really was a taxi run - why I felt I had to see what 10 degrees of flaps felt like remains a mystery. With a 10 kph headwind straight down the runway...well, the rest is now a piece of my airplane's logbook and my piloting skills learning curve.

 

The repairs are going well and I was fortunate the damage did not involve the engine, the firewall, the wings, fuselage or empennage. I did get the main gear spring straightened with two "cold bends" - one with a 10-ton press and judicious use of supports under the spring; the second by using a massive tubing bender around a suitably sized radius. The North American agent advised that up to three "corrections" can be made to the spring before replacement is recommended. This being said, the spring is bound to lose some strength and some flexibility each time it is flexed past its memory point. I've made a "spring-shape" template to use for pre-flight checks.

 

I read a while back that you were in touch with Eric Giles at World Aircraft Company. I actually bought my Savannah VG XL kit (Eric renamed them "VGW"'s from Eric's former company, SkyKits. I believe it was SkyKit's last sale before Valter della Nebbia acquired the North American distributorship for ICP.

 

I understand Eric's new line of airplanes (especially Spirit and Vision) are the brain children of the same Max Tedesco who worked with Chris Heintz to develop the CH 701 and later, on his own, the MXP 740 and the Savannah.

 

Fly safely,

 

Dan

 

 

[dan tonner]

It will explode in the press before you get it straight if it is that badly bent. They still make them, get yourself a new one. Have you ever seen this page before http://www.aerokits.net.au/prod04.htm , the first batch of them were fabricated out of the remains of the spring Reg tried to straighten, he keeps main gear springs in stock in Australia so your parts distributor probrably does the same.

[dan tonner]

Hello Rankamateur;

 

Thanks for the response, I appreciate all the input I can get.

 

I have gotten a lot of opinions on the question of straightening the aluminum main gear spring. There was a consensus that if the spring could be cold-bent to its original shape while maintaining significant "force-load" during the process, then a suitable repair would result. Use of heat was universally discouraged.

 

I took the spring to an industrial machine-shop, shared the opinions and the cautions and we gave it a go. The shape was restored to original. We matched the left side to the undamaged right side using a cardboard template which I'll keep for future pre-flights. I'll keep you updated if there is any deformation once the airplane is making more "normal" landings.

 

Is there an Aerokits for North America? The three-point door latch and the manifold vacuum gauge are of particular interest but I'm on the other side of the globe.

 

Fly safely, best regards,

 

Dan

 

 

[rankamateur]

The manifold pressure gauge is available anywhere (compusory in Australia where inflight adjustable propellor is fitted), the three point door locks are manufactured in Australia by the ICP importer, Aerokits, I am not aware of anyone copying them, yet. I believe the spring that Reg rebent was pressed cold and tore apart with a bang before it came back to shape.

 

 

[eightyknots]

Thanks for the reply Mark;I had already arranged the first flight to be handled by my Ultralight instructor...I think he was as excited as I was about getting my plane in the air the first time - he'd been watching the construction process, more or less, from the outset in 2011.

It really was a taxi run - why I felt I had to see what 10 degrees of flaps felt like remains a mystery. With a 10 kph headwind straight down the runway...well, the rest is now a piece of my airplane's logbook and my piloting skills learning curve.

 

The repairs are going well and I was fortunate the damage did not involve the engine, the firewall, the wings, fuselage or empennage. I did get the main gear spring straightened with two "cold bends" - one with a 10-ton press and judicious use of supports under the spring; the second by using a massive tubing bender around a suitably sized radius. The North American agent advised that up to three "corrections" can be made to the spring before replacement is recommended. This being said, the spring is bound to lose some strength and some flexibility each time it is flexed past its memory point. I've made a "spring-shape" template to use for pre-flight checks.

 

I read a while back that you were in touch with Eric Giles at World Aircraft Company. I actually bought my Savannah VG XL kit (Eric renamed them "VGW"'s from Eric's former company, SkyKits. I believe it was SkyKit's last sale before Valter della Nebbia acquired the North American distributorship for ICP.

 

I understand Eric's new line of airplanes (especially Spirit and Vision) are the brain children of the same Max Tedesco who worked with Chris Heintz to develop the CH 701 and later, on his own, the MXP 740 and the Savannah.

 

Fly safely,

 

Dan

Hi Dan, how soon before you can fly your XL/VGW?

 

 

[dan tonner]

Sorry about the delay Eightyknots, I'm actually visiting Italy as I write this.

 

ICP (through Valter della Nebbia, ICP's distributor in Texas) arranged to have the last of the parts I need sent to me here in Italy. Saves a bundle in shipping, and, most important, no waiting. I would like to be airborne before the first snow in Nova Scotia, but, if not, next spring. I took my time to get everything "just so" when I built my plane and I will insist on having the repairs "just so" as well.

 

I was very fortunate in that there was no major damage to anything other than my pride.

 

Best regards,

 

Dan