Supertweet

Holy Crapola! Do you think anyone could find more ways to NOT fly an airplane? 

The test pilot wanted the fuel system and throttles checked, and now it’s done. But we broke the left throttle cable putting it back together, and it took 4-5 months to get a new one in and working.  In the process, we found what went wrong. Turns out that there are jam nuts on the threaded ends of the cable. But when you tighten them into position, the front nut under the center console will have a tendency to turn the cable too as it tightens. This causes a twist in the cable making it subject to breaking. Unfortunately, the WARNING that is in the book is NOT in the same area as the cable installation–it’s further into the book.  Too late.

I’ve had some business and personal traveling lately and it took time away from the bird.  With cable in, I got the interior back together (a big job), the seats in, and closed up.  Only issue is that dang-nabbed hydraulic leak in the nose gear. 

So, the steering cylinder was leaking enough to warrant me taking it out and rebuilding the system.  To take out the cylinder you must take out the nose gear entirely.  UGH!!  I had to make a speacil tool to dismantle the cylinder which took a couple of days.  And, then it was time to take apart the cylinder.  It’s a complicated multi-shaft, multi port system.  One shaft had a pitted end.  Its out now and somehow I have to rebuild it.

Nose gear out to remove steering cylinder

Steering Centering Shaft with pitting

I’m thinking of using the HVOF system to build up the shaft then lap it down in the lathe.  This may take a couple of weeks to get someone to do the metalizing of the shaft. Keeping my fingers crossed.

Sorry for the delays. I am anxious to fly.

Tailwinds all.

After Airworthiness Inspection and Certification, all seemed going well. We called in the test pilot. We ran into a gliitch that I felt needed further investigation. Also, the pilot asked for a little bit more “cushion” under the throttle stops.

During throttle alignment, we found a tiny bit of play in the torque tubes that could mean a sloppy movement later on. So I elected to take the system out.  WHAT A MESS!!!! Jeez!  Whoever designed this mechanism is a sadist and a can short of a six pack.  Anyway, we got the things out, fixed, and back in.  Now time to re-set the throttles.

And guess what?  We somehow snapped the internal throttle cable.  So OUT it came, along with its attendant parts.  Now I am trying to find someone who make this cable to specs, and it is not easy. Its an unusual cable system.  I think we found a supplier, but will have to see if they can do what we want.  Next week will tell the story.  Otherwise we have to change to a different cable system, which I don’t want to do.

Broken Throttle Cable

Today, March 15, 2011, was inspection day for the A37.  The paperwork took 3 times longer than the aircraft inspection, actually.

Engine Start. FOD screen coming up.

We pulled the bird out, started it up, made noise, turned on the lights, flapped up and down, wiggled the wings back and forth, pulled the tail up and down, and did all kinds of magical pilot stuff.  After toggleling the trim up and down, left and right, back and forth, all the movements were correct and verified. He liked that!  Then I wiggled the nose wheel with the power steering to show that I really knew my stuff!

Ready to go

All paperwork was in order, except I needed to print out a new 8130-6 Application. Somehow I left my original at the office. So a print out and new signature finalized everything.

Ops Limits were as expected.  The DAR knew his regs and liked the airplane, so it went smoothly.

We celebrated with a big burger and beer at a local pub–11 years of work completed.  Now we just have to fly this puppy!

Over the holidays had my new electrical gurus going through the radios. Quick photo of them in action.

Finally, experts at work!

Well, for the first time I let my A37 go all out. 98-100% power on a taxi test at KTMB. Short-term full throttle due to the fact the plane accelerates so quickly to flying speed.

Had my son along to monitor gauges and speed. I think I could see his smile through the mask 10 minutes after we came back to the hangar and shut down.  He was grinning from ear to ear.

No surges, no fluctuation, no problems. Very smooth. Power response was perfect and aligned.  And with a 1 to 1 thrust to weight ratio, I pretty much felt what so many others have written about. This bird is going to be a dream to fly.

Ground handling was straight and true. Taxi on one engine saved fuel, noise, and money.  Only slight constant foot on the steering to keep ‘er straight. Used much less brakes ($$).

Acceleration was VERY quick!  From zero to 90 kts. in about 6 seconds. She wanted to fly. But I had no flaps on her so she sat on her legs properly. Any flaps and she would have gone airborne.

Tower had good things to say about the new bird on the field.  “She looks real good out there”.  Kinda made me feel good too.

Later

Well, got the aircraft out of the hangar this morning for some high-speed taxi tests.  It was great that everything went as it should, almost 100%. The bird performed flawlessly.

Pulling it out for first high-speed taxi

Only issue was a right-side oxygen regulator that got stuck in the closed position. The mechanic/engineer in the right seat couldn’t use it and did not know how to turn off the hot mic.  So I had a lot of background noise with his mask off. And the airplane is loud.

One thing I am going to start doing is taxiing on one engine.  Two-engine taxi runs eats the brakes, consumes way too much fuel, and doesn’t do a thing except burn dollars.  The mechanic doesn’t like that, but he’s used to much bigger prop driven planes.  I don’t need differential power for steering or speed.  Hell, it’s too fast as it is now.

No radio issues. All OK.  First taxi was moderate to 50 knots to check steering and brakes.  Then back around again for another. This time I held the brakes until 60% and let ‘er go. Power up to 80%. Even with that little bit she took off like a shot.  Up to 70 knots.  All OK.  Don’t really need to use power steering above 60 knots so I have to learn to turn it off as I accelerate.

Even with power at idle it does not like to slow down.  So thrust attenuators are a must.  Next power runs I will shut one engine down on runway as it slows.  Brakes are adequate, but certainly not going to write home about them. Just have to get used to the quirks of the bird until it is natural to the touch. Right now I am “thinking” about everything, and that’s not the way it is supposed to be done.

So, we put the plane away after 50 minutes of ground work, radio checks, accellerations and stops, steering, engine instrument checks, system checks, etc.  All perfect. And I used a lot of fuel just doing the taxi runs (2). Figure about 125 gallons.  OUCH!  It’s a hell of a lot more efficient in the air.

Perfect testing.

With the starter back in, it was time to turn them over and burn some fuel. Starts were prefect and cool.  All gauges readings perfect. No problems. So maybe time to drive it around.  Boy, is that bird LOUD!  Will have to be careful when operating or else I am going to annoy some neighbors.  You can feel the bird just trying to break loose, even at idle.  (By the way, it is best to taxi on one engine–too much power).

When we pulled the bird out of the hangar and lit her up, we had gathered a small crowd of gawkers.  They came out of nowhere with cameras, still and video. 

Left brake was “squishy”, if there is such a word. Decided to investigate before driving too far. Found a small hydraulic leak in the copilot’s master cylinder swivel inside cockpit (a common problem with these swivels).  Took some time this weekend and pulled it out and repaired, then re-bled the brakes, filled master cylinders. Now looks and feels ok.    Seeing as the bird was on jacks we did gear retractions, checked the gear horn, cycled all systems, etc.  Perfect.  Was dead tired after two days of tool thrashing, so we quit yesterday with almost half a day remaining.

Will do high speed taxi next. Will try to do this week, rather than waiting for weekend. Holidays coming up so time is squeezed for all of us.  With family coming in, it would be great to do some taxi tests with someone who can write down engine indications, call out ground-personnel checklist, etc. One runway is closed at KTMB which may be a good thing. I may be able to use it for taxi only without bothering local traffic.

If for some reason I do not post during holiday, may I extend my best wishes to you that are just “plane crazy”. May you have tailwinds and other good fortunes, all.

Charlie (Dragon 921)

Rebuilt starter went in (again!!) today. All locked up. And, took apart the intercom. The radio guru was able to rebuild the transmission amplifier. It works perfectly. 

It was interesting–the radio issue.  The microphone/earphone cable, (4-wire), is unshielded.  So it puts out a lot of RF. It jumps right into the transmitter with a loud squeal.  The amplifier fixed it. But I would have thought a shielded cable would work almost as well. 

Next time I’ll replace with a new type of shielded cable to eliminate any feedback. 

I was able to change the squeal by simply running my hand up and down the cable.  Learning new stuff all the time.

The Classic Jet Aircraft Association has an  upcoming annual convention in March at Nellis AFB, Las Vegas Nevada. March 17-20. My bird won’t be there but it is a good group. Hope to see you all there.

During pre-flight I have always spun the turbines over by hand to ensure no binding. Well, I’ve had this problem before and thought I had it licked.  But the right engine was stuck, and I knew why.  It was melted varnish from the stator.

How do you stop a jet engine? Melt the starter together.

This has happened before and we finally worked through it.  But it appears there is still some residue varnish in the stator that has leaked in between it and the armature.  So I pulled the starter and sent it to the shop for warranty repair.

YEP!  Same thing.  They’re as flumoxed as I am about this. Will get the starter back in this next weekend and turn it over.

Not often we find a photograph of our aircraft actually flying in its combat livery.