Alouette

[Lama Bear]

Ground resonance:

The Alouette is not quite as suseptable to ground resonance as the Lama but they share many of the same causes.

1. Improper greasing of the main rotor grips...If done wrong ithis can force grease past a seal and fill the grip putting the M/R system out of balance. The best test for this is to tap the grip with a metal object. A wedding ring works fine if you are so equipped. A normal grip will have a clear ring to it while the grip with grease will not.

2. Blade spacing cable mounts are not free.....Check to make sure they are lubricated and pivot freely.

3. Improper inflation of the shock struts....make sure they are right and equal. Same goes for the tires.

4. A weak or bad dampner..... drain, refill and bleed. Check the timing on them and make sure there is no air in them. This is an over night procedure.

5. Proper tension on the fuel tank support straps....Check their tension and security. This is more important than you would think.

Most ground resonance problems relate to one or a combination of these factors. However pilot technique is important. some pilots always seemed to have problems while others seldom did. Play with the pedals a little while your on the ground. Loading or unloading the tail rotor can affect resonance.

I'll try and remember some more. I haven't flown one since 1997 and my memory was the 2nd thing I lost.


Sticky pedals

The pedals should be smooth through their full range of travel. The most common problem are the "stack bearings" located in blade grips. There are three in each grip. They are the feathering bearings in this system. They can be installed upside down, causing problems, and they do wear out. The most I ever heard of from one set was 600 hours of heavy use. More common, with a GOOD mechanic was 400 hours. Usually the 1st indication was called "notching". The tail rotor would develope a resistance to pitch change that the pilot had to push through. Once past this area they again became smooth and easy. The mechanic could rotate the stack bearings and nurse a few more hours out of them but it was time to order new ones.

There is a hyd dampner on the tail rotor system located under the floor that has a quaint French name (whodaily???) that I can't remember now. It was very rare to have problems but it could also cause the resistance you talk about.

Now for the easy one. If the fuel flow is fully engaged it has passed a micro switch mounted on the fuel flow assy. It's called the two thirds micro switch and it's purpose is to prevent electrical engine shut down. If I am not seriously wrong, the big red "cherry" light on the panel is wired to this switch. I am away from my fight manual but I'm sure the check list calls for a check of the 2/3 switch prior to take off. If the flight manual doesn't call for this check you should do it anyway. I do know that every Allouette and/or Lama pilot I worked with checked it. Fully engage the fuel control and turn the switch off. Nothing should happen. If it does the 2/3 micro swtch is at fault.

Here's an interesting little foot note. You need at least 17-18 volts to shut the engine down. Less voltage than that will not operate the electric fuel cock. I once ferried one home with out a generator. By the time I got to the hangar I only had 15 volts and could not shut the engine off until I used the manual fuel shut off. This was done to completely remove the overly complex start system from interfering with engine operation.

When I went to Lama school in 1976 Turbomeca bragged that there had NEVER been an inflight Artouste III failure. Of course at that time all engines were sent back to France for overhaul. As soon as they let an un-named engine shop in the US overhaul the engines that record fell.

The Alloutte and Lama both require an EXPERIENCED mechanic. I CAN'T STRESS THIS ENOUGH!!! The machines can make 200 max power lifts a day, day after day, with the right mechanic and a steady supply of spares. However a pristine machine can be a flying junk pile in a 100 hours with out the right maintenance. The easy part is, what the manuals say is what to do and use. If some of the tolerances seem sloppy don't worry about it. If they are within specs they are good. You just have to keep a close eye on them as the machines are dirty (grease, 10 wt oil, 90 wt oil, and turbine soot) and this accelerates wear. Use PLENTY of lubricants, they're not that hard to clean and the components will last much longer.

If you have any thing else I would be more than happy to try and answer what I can. I just won't be able to access my books until I get back to the US the middle of the month. One of the best French mechanics I ever worked with is working down in Chile right now. How far are you from there?

Have a great time! They are great machines, built to work hard!!

Jim