My Moni Story

Jim Lewis
(818) 363-5116

Carlos:

John Shaw gave me your first two issues to read. The newsletter is a good idea and will be a big help for some of the builders who need a little help. I would only like to see it a little more upbeat, not so heavy on the Doom-n-Gloom. The Moni is a fun little airplane with no nasty vices. It is also a very different little airplane, different from the typical SpamCans that most of us learned to fly in. It is those distinct differences that surprised some of us. I know I had to go through a learning curve that I didn't expect. It would help the not-yet-flying members of the Moni crowd to be prepared for that when they get ready for their maiden flight. Perhaps those of us who have been flying now for some time can help.

Mine is #175, a standard 25hp, belly wheel model that has since been upgraded to 30hp. I finished it in 5 1/2 months and first flew it on July 13, 1983. It was four minutes old when I crashed it. Wind shear got me on very short final. Landing gear was a total wipeout, the propeller was turned into a 5x18, and there were numerous scratches and scrapes all over the plane. I was completely uninjured, only upset over what had just happened. Things weren't looking too good as far as Monis were concerned. The first one finished on the West Coast had been demolished in a stall-spin accident and now the second one, mine, was busted up too.

It took me a year to put it back together. Most of that time was spent just deciding whether or not I really wanted to try it again. I finally rationalized that it was a weather related accident and that the plane was OK. Since then, the Moni and I have become good friends. It teaches me something everytime I fly. Your newsletter would be a good place for me to pass along some of the things that I have learned.

Before I begin, I want to make some legal disclaimers. I speak only of my personal experiences with my particular Moni. Mine is not exactly like others, nor is it flown like others. I offer my experiences as an interesting story of my learning curve.

I think it would be wise for me to start first with the things that are the most serious, the things that will put my Moni down out of he sky. First is the propeller; everybody is having problems with props and prop bolts. I had about five bolts break before I realized what was happening. My KFM engine doesn't seem to have a very heavy flywheel built into it and the sharp power impulses are not damped out but instead transmitted directly forward to the prop. The propeller actually slips microscopically back and forth on the propeller flange when the engine is running. Even properly torqued prop bolts can't hold it. Take off your propeller and look at the rear face, the face that touches the engine prop flange. You may see black marks on the wood where it was rubbing microscopically back and forth on the flange, 100 time each second.

The construction manual warned us to be very careful not to let the prop bolts protrude too far into the alternator because the bolts would hit those expensive field windings and wipe them out. So most of us dutifully were careful to use bolts that were nowhere near long enough to hit those precious windings. But that put the clear portion of the bolt shank, that portion which is smooth above the threads, up inside the wooden hub of the prop. And only the threaded end of the bolt then stuck out of the wooden hub and passed through the steel prop flange. So, what I have now is two circumstances that tie together to make a marvelous little bolt cutter. It is lined up on the fragile threaded portion of the bolt which has all kinds of built-in stress risers and which has also been reduced to about 1/4 inch effective diameter because of the depth of the threads. Mine will beat through a bolt in as little as one hour. From what I have heard from others, it sounds like broken bolts and lost props are very common.

What to do about it? I carefully select prop bolts so that .050 of the clear shank protrudes through the wood hub and into the steel prop flange. -(I had better define the clear shank more carefully. The bolt has threads on the end, then immediately above the thread is a very small area with a chamfer which leads to the clear shank of the bolt. The shank will measure 5/16 in diameter and this is the part that I want to protrude .050 inch out of my prop hub.)- This is very touchy because I don't want it to protrude so far that the nut will bottom on the chamfer when I torque it down. It is essential that the clearances be checked on each individual KFM engine because there may be differences. My first KFM was not the same as the second engine. I have found that I must constantly retorque my bolts. I do my bolts about every 12 hours and, absolutely, whenever the weather changes. I have been known to retorque everyday because the weather had changed since the flight yesterday. It's the wet-and-dry changes that cause most of the trouble, I haven't seen temperature do much yet.

On my KFM, a standard AN-5 bolt doesn't reach far enough inside my alternator to hit my field windings. Even so, I have been sorely tempted to machine my threads down about 1/8th inch shorter just to be safe. But the FAA types hate to see bolts that have been fooled around with. However, I have been considering going with a shear nut and washer on each of those bothersome bolts so that I can let .100 of the clear shank protrude for a little more shear strength. If I find that those nuts are rated high enough in tension to allow that, then I will shorten the threads in a nice, neat, professional manner.

Now, after a bolt has been run about 20 hours, when I pull it out and inspect it, I find that the .050 portion of the clear shank has very mild gall marks on it where it has been beaten back and forth against the prop flange. In 105 hours, I have yet to have a prop bolt fail that was of the proper length. Sometimes I did have to use up to two washers to get the correct .050 protrusion.

John Shaw told me something interesting about all this. He told me that the KFM prop flange is actually drilled for 8mm bolts, not 5/16. I believe the 8mm bolt is about .008 inch bigger and that makes for loose fitting 5/16 bolts, which could account for the galling I have seen on my bolts.

By the way, I suggest no one use the MS grade bolts. I thought that because they are rated 180,000 psi that they would be better than the 120,000 psi rated AN bolts. But when I tried them I went through those suckers like popcorn. I guess they are too brittle. I went back to AN bolts and replace them about every 50 hours because I don't like looking at galled bolts.

Now for the last thing on my bandwagon: the canopy latch. Having the canopy pop open in flight is one of those things with a solid pucker factor 10 rating. I would definitely pee in my pants if it ever happened to me. On my Moni, it would not be the latch that is the problem, it would be the canopy frame that is the problem. It was made as per the construction manual and it's just a simple little aluminum tube frame, pop riveted in the corners and not at all rigid. Put a hurricane wind of 90+ mph against it and it will distort if allowed. Picture that left rear corner of the frame near your left shoulder. If there is room behind the frame, the frame will do a parallelogram trick. The left frame member will distort to the rear, taking the latch pins with it and unlatching the canopy. WHAMO!! Wet pants, right now! I saw this potential problem during construction after I had heard about John Monnett's canopy popping open during one of his flights.

What to do? Very simple. Put a block behind that left frame member. I used an L-shaped little piece of stainless steel that was pop riveted to the top left gusset at the rear of the cockpit. When I close the canopy, that left frame member comes down right in front of that little stainless steel piece. The frame can't distort to the rear and unlatch itself. Some of the other solutions proposed take two hands and a series of steps to open the canopy. I just give a gentle tug on my canopy handle and step out. I am a firm believer in the KISS principle.

These are the only two things I believe will cause problems due to the design of the aircraft. It is not a perfect design but with these two things taken care of, the Moni is a real ball, a wonderful little toy to be enjoyed. It's fun to fly around together with friends flying in their homebuilts. They kid me good-naturedly about my slow climb rate but I got them back one day. We departed California City glider port where I found a strong thermal right off the end of the runway. In just three turns, I rocketed up to 7000. Those stubby-winged homebuilts couldn't touch me that day and they haven't said much anymore about my climb rate since then. Of course, none of that stopped me from kidding them everytime in the fuel pits. They still envy me my $5 fuel bill when they pay their $24 to the man.

FLYING TIPS:

Two builders here on the West Coast have asked me about the best way to land a Moni. I don't know that my way is best but I'll pass along to the readers what I do to get mine on the ground. I discovered very early on that the stock Moni will bounce badly if the landing not is just right. I bent three axles and destroyed one black plastic (nylon?)wheel, one steel wheel and shortened one propeller by about one inch. I didn't know if my bank account could stand the drain until I would learn how to land this turkey. Then I decided to put a larger, fatter Lamb tire on so that I could run it at lower air pressure. I had to modify the fairing and the scrubber brake. But it worked. I run the tire pressure at 32 instead of 38 and almost all of the bounce disappeared. Probably some of this improvement came about because of improvements in my flying (landing?) ability but the greater part is due to the softer, fat tire.

I fly a pattern very much like a Cessna 150 would. I do that so that I can blend in with the existing traffic without disrupting them. You can imagine what a Beech King driver would be saying if he found himself number two behind me and I were flying the pattern at 48 mph. So, I fly the pattern at 70 and I maintain the same altitudes as the others. When I get on short final, I gently pull full spoiler and pull the nose up to bleed the speed off. I time this so that I cross the fence at 55 mph and as I cross the fence, I gently dump the spoilers back to half open. As I pass over the numbers, my speed is below 50 and I stop looking at the instruments. I concentrate on the runway centerline. I try to hold the plane six inches from the runway while holding half spoiler. I try to do this for as long as possible. Eventually, the plane gently sinks through the six inches and touches the runway. The instant is touches (NOT BEFORE!!) I nudge my stick forward about 1/2 inch to nail the plane down. Generally, I land in such a short distance that I have a long way to go to a taxi turnoff, so I just coast along. As I coast along I push the stick further and further forward to take the weight off the tailwheel.

TWO MINOR POINTS:

Those black plastic wheels seem to blow apart at the rim due to the 38 psi and the pounding they take on landing. If somebody tries them with 32 psi Lamb tires, let us know if they stand up better with that set-up.

In the beginning, I found that, after landing and on roll-out, when I gave it throttle to get off of the runway, my engine would die right there in front of God and everybody. With a Beech King right behind me on short final, I tended to sweat a little until I could get it restarted. Then I discovered that my engine CHT needle was resting down on the bottom peg of the scale after landing. What had happened was this: I close my throttle when I am abeam the tower on downwind. The entire last half of the pattern is flown with the engine idling. By the time I get down to the runway, it is stone cold. It needs a one or two second shot of full choke for it to run right again. I push the throttle lever and choke lever forward together. After about one second, I let my thumb slip off the choke lever while I hold the throttle with the palm of my hand. I don't sweat much anymore.

Jim Lewis

Editor's response: Thanks for your input Jim. It is not my intent to make a "Doom-n-Gloom" newsletter and I agree with you, the Moni is indeed a FUN little airplane. However, I think the Moni's present safety record is telling me otherwise. There are problems out there and we need to be as aware of them as we possibly can. These are problems related to both the aircraft as well as its pilots. As you have pointed out, the Moni is nothing like the "spam cans" most of us learned to fly in. Personally, I would not consider the Moni an "easy" airplane to master, especially for a low time pilot whose only experience has been flying a 152. I know this is a controversial subject, and judging flying skills and handling qualities is at best, extremely subjective. I believe it is up to each individual to prepare him/herself as best they can for flying the airplane. Perhaps we can have a column dedicated to how it's best to prepare to fly the Moni as well as for normal flying techniques.

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