700 crash Help!

[Sieze2]

Ok Just tested the uniflow and header setup for its first flight. Everything was fine. Landed and checked engine temps, was perfect. Anyway. Suddenly the engine made a terrible sound, and the tail started piroing, and I lost power big style. I autoed it fine, but because the tail was out of control, it hit ground. Inital impression was the engine had blown a hole in the piston, but it was happily idling away to itself and sounded fine (and has lots of compression).

The tailblades, 1 grip, and the torque tube gears are damaged, one grip link is cracked and had come off. Main blades are fine. The gyro and tail servo is fine, and the pitch slider is all complete (the plastic grip has literally snapped off). I had a bit of an issue draining the tank with the pump. It was fine when the fuel got in the pump,. but till then I had to spin it like crazy. Does this mean I could have a leak in a clunk?

I feel the piroing could have been due to a low headspeed, because of the ball link comming off the blade grip? It only had a crack in it,. its not like it had blown apart. Any other opinions? Could it be a fueling issue? Should I take the head of the engine?

[robgt]

Hi Oliver,
Have you made sure to open the clips to carb and muffler before flying?

The engine will run for a little bit (suprisingly) with the back pressure line clipped shut (ask me how I know ) but it will end up choking the engine and running badly.

Not sure why the tail would start piroing on it's own though?
I'd need to see it??

Cheers,
Rob

[trebor27]

Were you using a governor? If you threw a governor magnet and had no backup throttle curve to fall back onto you might see a sudden and dramatic cut in power....

Just a random thought...

Rob

[moyesboy]

I'm betting you will find some damaged gears in there somewhere, or a knackered one way (lost drive to tail).

[Sieze2]

The torque Tube gear in the heli has failed. The heli flys fine without the govenor using v curves, so I don't think is is that.

Rob the clips were fine. I checked them at the crash site. Besides it had flown 7 mins beautifully.

What about the symptoms of the refueling pump?

[robgt]

Possibly an air leak somewhere - check fuel pump lines, then work your way into the heli to make sure they are all airtight.

It's normal to have to get a fuel pump "started" when filling/emptying - I take it this was excessive somehow?

Cheers,
Rob

[Sieze2]

Instead of it taking 10secs it took 30 secs of fast winding to get the fuel back into the pump. I emptied the pump lines and tried refilling the tank. It took about 10 secs to get the pump going again. It only seemed hard to prime when sucking from the heli.

I will go over the throttle and fuel lines tonight. The engine sounded completely different when she came down. It has to be the fuel/carb, or just serious bogging as only one blade was generating lift? I can't help but think the link has cracked and poped off the grips in flight. The engine was running sweet as a nut, then suddenly lost headspeed, tail authority, and sounded terrible.

Another problem I have is the pitch slider for the 700 is not yet available as a spare. I only need the plastic bit that connects to the blade grip. Does anyone know if I can use the same bit from a 600?

[robgt]

What hand fuel pump make is it you're using?

The muffler hasn't come loose has it??

I really need to see the heli to get the niggles ironed out
You up the Coven field on Saturday by any chance?

With the tail rotor hub being the same as the 600, I think the pitch slider should also be the same (if for no other reason than geometry) but don't know for certain.
Cheers,
Rob

[robgt]

As luck would have it, Align have just released that part...

Part number HN7079.

It'll be over here soon.
Cheers,
Rob

[mark Taylor]

the quick uk tail grips are the same on the 600 and 700 so i reckon the pitch slider will be the same ?
cheers

mark

[heliward0]

What hand fuel pump make is it you're using?

The muffler hasn't come loose has it??

I really need to see the heli to get the niggles ironed out
You up the Coven field on Saturday by any chance?

With the tail rotor hub being the same as the 600, I think the pitch slider should also be the same (if for no other reason than geometry) but don't know for certain.
Cheers,
Rob

exhaust loose or a missing bolt eh rob!!!!

[robgt]

Grrrrrr
How do we think I know about that one then eh!!
LOL
Cheers,
Rob

[trebor27]

Possible hand-pump symptom.....
On my 600 nsp my hand pump was sucking air when trying to empty the tank.... It turned out not to be a problem at all, but what caused it was the fuel line had got glow fuel on it and was slippy. As a result if I went mad on the hand pump trying to empty it in record time the fuel "clip"/"slider"/"pinch thing" would slide open and air would get sucked in through the carb.... That’s all...
Now assuming the 700 has the same 3-way filter for tank/carb/filler, look closely at the filter and see where the air is coming from... Mine was coming from the direction of the carb, not the tank.

Possible leaning out during flight:
Check your clunk line length, on my 600nsp it was a fraction too long and allowed the clunk to “stick” to the back of the tank. By stick I mean with the open hole flush against the back, I never flew like this and just shortened the clunk line by 1mm to give clearance so the back of the tank couldn’t clock the hole in the end of the clunk..... (I know the 700 tank is different, but worth a look!)

[Sieze2]

Ok Basically the 500 uses the same final part of the slider assembly, so thats all sorted.

The symptoms from the hand pump was a bit of a red herring, basically the pump primes faster when it is held close to the ground. When held as high as the lines allow, it takes alot longer to prime, as you have to pull the fuel up the line against gravity. Bit embarrasing really.

I still feel the link broke in flight, and the engine bogged down, and piroed due to low headspeed. The problem is quick UK haven't got a complete solution yet (especially as its the blade grip link that breaks according tot he forums (and my experience). I don't really know what I am going to do. I know I have 8 gallon arriving on wednesday, and a burning desire to fly it !

[electricsceadu]

the blade grip link isn't a problem
across the pond they use the raptor 90 se blade holder stand off PV0400
I custom made a stand off for mine
and i used the rod from the 600's flybar cage and shimmed it to take away the end float on the cage
my 700 has no align links on it
some also use the MA links
quick uk are working on the parts for the 700, so lets hope they get them out soon