Aerotrike Cobra Undercarriage not aligned straight

[le boss]

I need some expert advice on the following please.

I have an Aerotrike Cobra with a full fairing. It has an 582 blue top motor and 3 blade Warp Drive prop.
The wing is a Spirit 15.
Originally the trike had a Rotax 912 but the first owner replaced the motor with a new 582 motor.

After I bought the trike and for my own peace of mind I took the trike to Petit Airport and commissioned Jenya to inspect the wing and replace everything that needs replacement like cables etc.
The bottom bracket of the main pilon tube was apparently worn and slightly bended so a new bracket was ordered and fitted. Jenya then flew the plane and according to him it flew straight and level.
I have also asked Andre Maartens (AIR O' CRAFT SERVICE CENTRE) to service the motor and inspect the under carriage. The Cobra was given a clean bill of health and was subsequently AP’ ed by Andre.
An ATF was issued and the trike was delivered.

I went flying on Saturday (26\01\13) and found the following:

The undercarriage is not aligned straight with the wing. It aims to the left relative to the wing by quite a few degrees.
On inspection I found:
1. There is a very distinct engine offset to the right. It seems deliberately designed
that way but keep in mind that the trike was previously fitted with a 912 motor.
Could this be significant? The modification was apparently done by an approved AP?
2. I know that the wing is trimmed to fly straight and level (Jenya) so I do not want to make
unnecessary adjustments to the wing.
3.I know that the hang block and brass bush has no significant wear because these were
checked by both Andre and Jenya. during service.
4. Can the hang block be adjusted in any way and if so, where?

How can I correct this alignment problem.

I will appreciate any help or suggestions and promise a case of Castle Lights to the anyone who come up with the right answer.

[mulderpm]

I am not an AP nor an expert, but from my experience, the aircraft will always point in the direction perpendicular to the propellor and in line with the crankshaft. IAW in the direction of the thrust. Therefore, if your engine is off set from the cart the whole cart will fly screw relative to the wing. On most aircraft the engine is off set from the fuselage, this is to counteract the torque of the prop and crankshaft...this is NOT the case for a Rotax 503 or 582. I do not know if this is the case for a 912? So, judging by some components being bent, the aircraft may have been in an incident, which bent the engine mount or the 912 engine is off set. In either case the quick and nasty fix is to fit spacers to straitened the engine or in the long term, to replace the engine mount with a new straight one (for a 582).

You can check trueness by clamping a long straight piece of angle iron to the block of the 582 engine. Line this up visually with the cart and/or the pilon. Off sets of a few millimeters are visible in this way.

Hope that helps le boss.

[Loco]

Hi, does it affect the flight i.e. does it pull in a certain direction or is it just aesthetics you're worried about? If the latter I would personally just leave it since both Andre and Jenya signed it out...

[mulderpm]

I would fix it. It puts unwanted stresses on the other airframe components. The aerie was not designed to fly like that...and although trikes are very strong when used as they were designed...they are not if you deviate from the design. Put a trike on its side and almost everything bends.

Le boss, have another AP inspect the problem. Try Hans Schoeten from...The Cabbage Patch Kids...Microland. He is excellent.

[le boss]

Ek het die vorige eienaar geskakel en die probleem vir hom gestel. Hy se hy was bewus daarvan maar dit het hom nie gepla nie. Vir my is dit egter n probleem. Daar is verder niks fout nie en die vliegtuig hanteer oor die algemeen baie goed.
Ek begin al hoe meer dink die alignment van die enjin is te kwaai na regs net soos Mulderpm hierbo verduidelik het.

Waar kan ek uitvind wat die korrekte alignment moet wees?

[Loco]

Ek het die vorige eienaar geskakel en die probleem vir hom gestel. Hy se hy was bewus daarvan maar dit het hom nie gepla nie. Vir my is dit egter n probleem. Daar is verder niks fout nie en die vliegtuig hanteer oor die algemeen baie goed.
Ek begin al hoe meer dink die alignment van die enjin is te kwaai na regs net soos Mulderpm hierbo verduidelik het.

Waar kan ek uitvind wat die korrekte alignment moet wees?

Praat met oom Alex Rudd...

[nicow]

Ek het die vorige eienaar geskakel en die probleem vir hom gestel. Hy se hy was bewus daarvan maar dit het hom nie gepla nie. Vir my is dit egter n probleem. Daar is verder niks fout nie en die vliegtuig hanteer oor die algemeen baie goed.
Ek begin al hoe meer dink die alignment van die enjin is te kwaai na regs net soos Mulderpm hierbo verduidelik het.

Waar kan ek uitvind wat die korrekte alignment moet wees?

Ek dink nie dit is die engin nie,die vlerk bly reguit langs die runway (maw hy hou sy rigting)maar die karretjie draai dwars.Jou rigting sal verander as die enjin skeef is.Dink aan hoe die trike maak as jy skeef sit(gewig verander)dan vlieg hy skeef....

[mulderpm]

Almal, my trike het soos le boss beskryf het gemaak. Ek het die engine met spacers reguit gemaak totdat ek n' nuwe engine mount kon bekostig. Die monteering is toe met n' nuwe een vervang. Die spacers en die nuwe monteering het die probleem opgelos maar die spacers was n' work around. Vra vir Oom Hans of Alex om jou te help. Dit is heel moentlik dat, omdat die 912 so feel meer krag het, dit nodig is om die engine te off-set?

As die vorige eienaar nie n' incident gehad het nie dan is dit heelwaarskynlik dat die 912 engine monteering n' off-set het?

[mulderpm]

Le boss jy kan vir Sout...Walter, by Rainbow Aircraft bell...zero ate too 6 seven tree one 7 six 3, zero ate too ate too nine zero 7 three 7.

[Nacho]

Take it in to the original manufacturer and let them check it out and fix it for you.

Rainbow. Don't take chances! My Cobra use to pull a bit when I pulled the wing in and reached 78 - 80 mph. Not a great feeling pulling bar in and fighting at the same time. Get it fixed. Can be a few things, but as I said, talk to Rainbow.

[mulderpm]

Spoke to Sout. There are two problems...1) the 912 is off-set because it develops significantly more horses than a 582. (100 compared to 60) the 582 is not off-set. 2) the prop rotation for a 582 is opposite to the 912...therefore the off-set is also in the wrong direction for a 582. This aggravates the skewness of the cart.

He also asked me.."why did he change to a 582?"

I agree ...take it to Rainbow Aircraft, there is no higher level of expertise than the manufacturer.

[le boss]

Some answers to the questions posted.

1. No incidents was reported on this trike. I checked with CAA and it was confirmed.
2. I am the third owner. The previous owner bought the trike with the 582 already fitted.
3. The initial owner apparently took the 912 out to be fitted in another aircraft. The 582 was brought new and fitted to the Cobra. (Thus the Hobbs difference between frame hours and enjin hours. - 67 Hrs)
4. The enjin mountings for the 582 does not look suspicious.
5. The current offset of the enjin I would imagine is between 5 and 8 degrees to the right.
6. If I measure the offset of the enjin via the centre of the prop blades from both sides to a fixed point in front of the cart I find a difference of 40 mm. (Left side is shorter)
7. When the trike is stationary and the wing is exactly level and straight the nose tip of the wing align perfectly over the nose of the cart. But when the trike flies the cart tend to aim to the left relative to the wing by about the same degrees the enjin is offset to the opposite side. (Remember the cart aims left and the enjin is offset to the right.)
8. I don’t know whether the enjin mounting bracket for the 912 and 582 are the same. The Cobra’s 582 was fitted by an approved AP so I would imagine he would have considered the offset prior to modification.
9. Nicow raised an interesting point though. The cobra measured heavier on the right than the left hand side. (About 2 Kg) But if this was significant wouldn’t the card rather pull to the right instead of to the left…?

Is there somebody prepared to fly the Cobra from Warmbaths to Rainbow aircraft on short notice?

The case of Castle Lights are still up for grabs.

[le boss]

Almal, my trike het soos le boss beskryf het gemaak. Ek het die engine met spacers reguit gemaak totdat ek n' nuwe engine mount kon bekostig. Die monteering is toe met n' nuwe een vervang. Die spacers en die nuwe monteering het die probleem opgelos maar die spacers was n' work around. Vra vir Oom Hans of Alex om jou te help. Dit is heel moentlik dat, omdat die 912 so feel meer krag het, dit nodig is om die engine te off-set?

As die vorige eienaar nie n' incident gehad het nie dan is dit heelwaarskynlik dat die 912 engine monteering n' off-set het?

Dankie mulderpm. Jy is die 2 de persoon wat die enjin se offset op die trike bevraagteken. Gister het iemand ook dit as n oplossing gestel. Die vraag is hoe reguit moet die enjin agter die trike wees...?
Ek is bang om sommer hals oor kop te verander sonder dat ek heeltemal seker is.
Dalk is my kas Castle Light oppad na jou toe...?

[Nacho]

Rainbow!

[mulderpm]

Rainbow!

Met n' 582 op n' cradle rubber mount, hoe nader hoe beter