| Author | Message | ||
     Bruce Newlan |
Speaking of gear legs, I designed longer gear legs for my tail dragger version of the S-90 in order to meet the measurements in the EDI manual. Now after getting the plane assembled and installing the legs, the plane appears to be nose high (about 14" of prop clearance)and I may be able to return to the original length. However, I suspect that I may have the same problem as John Kee with his tail dragger. He designed a new set of legs where the major bend is offset a few degrees rather than 90 deg to the leg. My problem with either the long or short legs is the fore and aft movement of the gear. It is between 1/2 and 3/4 inch. The gear goes through Rib "Q" that has a 1/2" aluminum reinforcing plate with a slot that is a little wide allowing the side movement. John made a new steel plate that accurately fits his legs and prevent this, however I think that I will make an aluminum saddle and leave in the aluminum plate to hopefully prevent this. This gear is supposedely designed after a Cessna 180, so I wonder if anyone knows how they prevent this looseness. The EDI manual says to shim the end of the gear (attached to Rib "I") with no mention of how or where. It's not conceivable to me how to prevent the above problem by shimming the end of the gear. There's about 3 feet of diagonnal leverage from the end to the wheel. Comments from anyone? | ||
| Larry Hoppe |
Let's continue the landing gear discussion started in the aileron section under a new heading. Tom Hutchinson, maybe you could move the last message in the aileron section to this directory. Has anyone compared the aluminum alloy landing gear (made by Grove Aircraft Co.) weight to that of the current fiberglass main gear? Being a metallurgist working in a large aluminum rolling mill, I would think that the heat treated Al maingear would have much more flex (delta between ultimate and yield tensile strength) than a fiberglass version. | ||
| Bruce Newlan |
Regarding lighter landing gear, I looked into a Titanium gear quite similiar to the physical size of the steel gear. I investigated an alloy of 94% Titanium and 6% Auminum.(being used in military aircraft) It saved almost 50% of the steel weight,. Being near the C.G. that went right to increased payload. The problem was cost. A single leg blank was over a grand and then it would have to be laser cut and bent. However, if enough quantity were ordered, the cost could be reduced somewhat. If anyone is interested further, please contact me. | ||
| Tom Hutchison |
My only experience with the fiberglass gear was in 90ED the "old" factory demonstrator. When Larry was letting me shoot some T&Gs, I dropped it about 3 feet onto the RWY. The resulting "landing" made an awfull sound and a definite feeling in the "seat of the pants". There was no bounce at all. If I had done the same thing in a C172, I would have bounced about 5 feet into the air. It was a good demonstration of the strength of the fiberglass gear. Tom | ||
| LOUIE LACY |
WOULD SOMEONE COMMENT ABOUT PUTTING THE NEW IMPROVED BRACKETS ON THE STEEL GEAR LEGS.THE OLD BRACKET HAS FAILED ABOUT 3 TIMES THAT I HAVE HEARD ABOUT SO I ORDERED THE NEW ONES THAT HAVE MORE FLANGES 3 INSTEAD OF 2 AND I ASSUME MADE OF CROME MOLLY INSTEAD OF COLD ROLL. HAS ANYONE EXCHANGED THESE BRACKET AND HOW DID YOU MAKE SURE THE ALIGNMENT WAS CORRECT.SEEMS TO BE A PROBLEM BECAUSE THE OLD BRACKETS HAD A SLOT AND THE NEW ONES DO NOT. LOU LACY | ||
| Glen Farley |
Another landing gear question: Does anyone have the specifications for what level the steel gear from EDI should be strengthened to? I want to start calling around to find someone in the area to heat treat my gear legs- but I do not know what to tell them so far as the specs required! Thanks, Glen Farley - Ohio | ||
| John L. Pels |
The steel legs have had a not so checkered career. The factory will not support them in any meaningful way. They are regarded as another cost-saving misadventure by EDI. I am buying the Fibreglass legs from Larry Olsen at Express. He has advised us of the likely incipient failure of the steel legs. Pay now or pay later. | ||
| Don Pugh |
This is the first mention I have heard of the steel legs being a potential problem. I thought they were to solve a problem with the fiberglass legs. I have both, the original ones from wheeler and the steel ones from EDI. Which should I use? | ||
| jerico |
Dear Gang, I guess it is time get into the swing of the gear leg topic. I have the steel legs on my Express and they are serving me very well. They are from EDI. I had the good fortune to be able to pick 2 out of 5 legs to get them as close as possible to being the same. It seems, and I have seen a lot of them, that they are all a little different. Do not use the original Wheeler legs. When I was involved with the Wheeler program, there were 3 sets of legs made with proper layups. One set was used on the demonstrator, one (maybe 2) to Mike Betts in Canada, and one to Jim Warner (of Grass Valley, Calif.) who finished and flew the first customer built Express. He beefed his legs up to get the results he wanted and they are still on the airplane after over 700 hrs and many landings. There is nothing wrong with most of the steel legs from EDI and the aluminum block and "U" bolt bracket system is Ok as well. The inboard rib "J" bracket system is where the trouble has been. I was fortunate in that I was at the factory and took delivery of one of the first sets made and welded by Mike McDaniels. Mine have been fine so far. Later "rib J" bracket sets have failed and have been replaced by new ones furnished by Larry Olson of Express Aircraft. Even there, a design change has been made of late. The recent brackets are just fine and compliment the rest of the system using the steel legs. The biggest problem with these gear legs has been to get enough positive camber. I made actual measurements at empty weight and at gross (putting 1000 lbs of cement blocks on the wings for gross) and found that the wheel spread was 5-1/2 inches under load. Obviously, the camber changed but mine went to "0" at gross while having been nearly 6 degrees positive at empty weight. Those are the figures I would use again and suggest to those that are using the steel legs to consider the same. The other consideration is the tow in or tow out? On tricycle gear airplanes the wheels should maintain a slight tow in for directional stability. Tail draggers should have the opposite with a slight tow out according to the information I have read. Again for directional stability while taxiing. I am not trying to discourage anyone from using the new fiber glass legs that Larry Olson is furnishing. I do encourage you to take advantage of the investment you have already made in the existing steel gear legs if possible. You may wish to contact Bob Gisburne of Arizona and discuss the issue with him as he recently changed from the EDI steel legs to the new fiber glass ones. gisburne@neta.com If any of you want to discuss this with me personally, page me at 1-888-849-0747 and I will return your call. Or, you may catch me in the evening at home here in California at 559-683-5918 . I have been flying my Express for 4 years now and have 290 hours of very satisfactory flying. I hope you have seen and read the Cafe Foundation article that was published in the Sport Aviation magazine just over 2 years ago. I can help you with many other questions that you may have. Although my web page is not up to date with current subjects, I see that most are still the same. Please check the articles there. http://www.sierratel.com/jerico Cheers and good luck to all you new builders. Jerry Sjostrand | ||
| John L. Pels |
As always, Jerry is the last and best source of information on anything Express related. The failure mode I alluded to only referred to a change in suspension geometry over a period of time and certainly not a catastrophic failure of any kind. I would be the last person wanting to disseminate bad Express info of any kind. Thanks Jerry for the clarification. John Pels | ||
| Sven-Ake Eriksson |
As I know there are some people that have had 'bad luck' with the nose gear strut from EDI. Are there someone that can give me first hand explanation on what actually happened and how the construction looks like inside the strut tube in the spindle area. I do have an EDI nose gear strut and I would be interested in info to see if there are anything that can be done to 'fix' the problem. | ||
| Bob Gisburne |
Ahhh... the saga of gear leg issues. My experience follows ... I have an EDI kit S-90 conversion w/ IO540C4B5. Empty weight is 2,040 lbs. (Lots of toys!) Nose Gear: I had the EDI nose gear. Discussions w/ Larry Olson indicated a poor design with little strength at the strut to spindle intersection. I shipped mine to him for a gusset-ectomy. Upon receipt Larry's firm (Express Technologies) would not install the gussetes due to poor design and build quality. Result, purchase Express Tech nose gear strut w/ gussets. No issues in 310 hours TT. Nose Gear Donut: The Wheeler and EDI kits came with a T-bar connection between the engine mount and nose gear strut. Express Technologies was selling a donut t-bar (ala Mooney landing gear) intended to absorb shock loads rather than transfer them to the airframe. In 310 hours of flying there appears to be NO movement of the donut in its retained slot. After my landing "incident" (coming soon) I replaced the donut with the original EDI t-bar and have felt no ill effects. Steel Gear Legs: At about 225 hours total time, I noticed that the left wing seemed to be sagging. Investigation revealed a bend occuring about 8" above the knee in the gear where the axle mounts. Hmmm... removed the gear and after LOTS of discussion with EDI, the gear maker (an auto spring maker) and a local materials test lab, I proceeded to temper, bend, anneal and re-heat treat my gear. It worked great! I can dig up the Rockwell hardness data regarding the heat treatment if anyone needs it. The Landing Incident: 11/28/98 5:05pm Carefree Airport, AZ After a sunset flight I returned to my homebase. Earlier in the day I had made a circuit of seven airports in AZ, please 5 practice ILS approaches at Casa Grande. Feeling pretty good. The airplane was 6 hours TT since annual, 306 TT. Normal landing, touchdown at 70mph. Hold the nose off like a Bonanza driver (remember BIG tail), apply light braking and the problems start. Slight vibration on right gear, quickly to severe vibration, then POP, the right wing drops 2 feet and sparks are flying off the step as it drags the runway. Hard LEFT brake to stay on the 50' wide runway as we are heading right FAST. Right main drops off the runway and hits our glider proof, concrete mounted runway lights and spins the airplane hard right at which time the left wings drops 2 feet. Damn... back on the runway and we are riding on the nose gear and the tail. Finally we stop, hop out and assess the damage. Thank god, no one hurt and no prop strike. Clean off the runway as a local Bonanza can't land til I get my airplane and parts off the runway. Six beers and a lot of huffing and puffing gets the airplane in the hangar. I remove the inspection cover from the right inboard wing. POW! I get hit in the forehead with the inboard attach fitting and an AN6 bolt/nut. Another six beers and I remove what's left of the inboard attach fitting. Findings: (1) single weld on the outboard side of each tab, (2) weld penetration is less than 10%, (3) rust formed under non-penetrated area, (4) butt weld, no slot in the base for the tab, (5) very nice white powder coated attach fitting may have hidden any cracks, (6) did not receive bulletin from Express Aircraft on earlier incidents. Fast Forward 12 months later... The aircraft is repaired, using Express Aircraft fiberglass legs and attachments. Reported slip in replacement for steel legs is a crock. Re-drilling, bracket rework, mill fiber plugs, etc, etc. First taxi is OK with no wheel pants. We put on the wheel pants and high speed taxi again. BIG TIME VIBRATION starts ASAP!! What's up??? Pull off wheel pants, no vibration... While moving the airplane by hand, the right main falls in a tiedown chain depression (you know 1.5 - 2" deep, 12" diameter. We hear a BIG POP!! There is a six inch crack on the inboard side of the gear leg starting at the bottom. Shining a light on the area reveals a number of air voids in the lower gear area. DAMN again... Fast Forward two months.... New gear leg installed. Airplane painted (its really nice, no more Desert Storm) taxi test with gear pants on. BIG TIME VIBRATION! Remove gear pants and the aft end of the pant attach bracket comes off in my hand. DAMN once more... Throw the gear pants in the plane and off we go. Fast Forward one week... with the help of the ever helpful Jerry S. we start in on the problem. (1) replace 0.93" Al attach bracket with 0.125" and NO lightening areas, big and beefy!, (2) Jerry remembers that some Glasair FTs had problems with wheel pant balancing. We check mine and MAN are they heavy AFT! (3) balance the pants with lead shot and resin in the nose (about 1.5 lbs). (4) Make sure the inboard gear fairings are installed as they are the final capture of the assembly to the gear leg. Fixes the vibration!!! In subsequent discussions with Express, two other aircraft have exhibited this wheel pant vibration issue. One recently switched from Matco to Cleveland brakes. I have Clevelands. My conclusion is that the glass gear are OK, but are VERY weak in the rotational axis perpendicular to the ground. Perhaps a wrap of BID from say 12" up to the end of the gear could help... The balancing and thicker brackets are probably just a bandaid for a problem that needs a real solution. I guess that why they call 'em experimental! Bob Gisburne N4382A | ||
| Bob Gisburne (Gisburne) |
The gear leg saga continues... Wednesday morning after a short hop from Carefree to Stellar Airpark and back, I add fuel to my Express for a quick trip to Mongomery Field in San Diego. 60 gallons of fuel, one person, baggage and some test equipment. As I taxi up our taxiway, a loud POP (reminiscent of previous explosive noises, previous Postings) and the airplane wants to turn HARD right. Shut it down, jump out and the right tire/wheelpant is tilted at an ugly angle inward. Remove the wheel pant and discover that the fiberglass gear leg has fractured eaither side of the axle backplate approximately 6" up the gear leg. (Looks like it going to be Southwest Airlines to San Diego...) Jack up that side of the airplane and drag it back to the hangar. This is the SECOND time this has happened to my fiberglass gear. The first time, the crack was discovered while moving the airplane by hand. Discussions with Larry are ongoing and I understand Larry has seen some other evidence of this problem and is working on potential solutions. But several other fiberglass guys are quite happily flying with no issues. Some ideas... 1. I experienced SEVERE vibration (so severe, I never accelerated above 30kts) of the gear legs until I balanced the wheelpants and beefed up the wheelpant attach brackets (0.090" to 0.125"). Perhaps this vibration induced some stress fractures in the gear leg? 2. I had experienced SOME tire scuffing due to toe/camber settings. Perhaps this induces stress? 3. I need to lose some weight. Perhaps my rotund figure is overstressing the gear? 4. I am a crummy pilot and always land three feet above the ground and deserve to replace landing gear every 75 hours? Perhaps I should ask for my money back from my flight instructor... 5. There is some manufacturing/design defect in the gear that is not apparent until after some time? Stay tuned for digital pics and analysis... anyone looked into the aluminum gear potential??? Bob Gisburne N4382A gisburne@technolabinc.com | ||
| jharlow |
Bob, Sure sorry to hear about your gear problem. If the problem turns out to be a pilot overweight problem, my wife will for sure cut out my beer and pizza. (hey Rob!!!, we may be in trouble. LOL) I'm also setting on glass gear legs and very interested in the full analysis. Keep us informed. Overweight John | ||
| llacy |
John On another subject how did you solve your fuel flow problem with the VM1000 I think I will have to move the sender between the fuel control and the flow divider. I suppose I should have put it there to begin with but what about the heat? Comments | ||
| jharlow |
As of now the problem has not reoccured since I went over all of my grounds. My sender is still mounted on the firewall after a 12 long straight sectionfrom the elect pump and before the mech fuel pump. I am also worried about heat and vibration if I mount the FF meter on the engine. In over 40 hrs I didn't have a problem so I not sure that mounting it on the engine is the final solution/cure all but I could be wrong. John | ||
| Bill Copeland (Cbros) |
John/Louie: Our Transducer is also located between the boost pump and the engine driven pump and is mounted near the center of the firewall (engine side) It seems to be working well. I am sure that Micro Vision recommends against mounting on the engine. What are the symptoms of your problem Louie? We thought we might be having a prob with our VM 800 system, but it turned out to be a very lazy engine driven fuel pump. Johns suggestion of checking the ground and shield connections has merit, as we experienced a widely fluctuating oil pressure reading which we traced to a loose connection on the CPU. Bill C | ||
| llacy |
Bill I think my problem might be the engine driven pump also Plan on replacing it today. I thought about doing it myself but was told I could do about $4000 worth of damage so think I will pay mechanic(cheep).I am getting low fuel pressure about 14psi at higher altitudes 9000ft.Bill on anothe subject do you have an drawings for an aileron trim tab and do you know anyone who has installed one. I have a left wing heavy Lou llacy@netease.net | ||
| Bill Copeland (Cbros) |
Louie: I know of only one EXPRESS that has a roll trim tab installed. Hardy Huber used the small area of the wing trailing edge between the aileron and wing tip. He hinged it similar to the aileron and I believe drives it with a MAC servo. Before you go to the trouble and expense of installing such a device, try loading the co-pilot seat with 150 to 170 lbs and see if that doesn't cure your problem. Bill C | ||
| CHARLEY SCOTT (Hogfan) |
In regards to the Vision Microsystems fuel flow transducer location, I have had mine mounted on top of the IO360 Lycoming engine for the past 900+ hours with no problem except the impeller wore out at around 700 hours. Replaced the complete unit. I have been pleased with the VM system and the co. support. Charley Scott | ||
| John Hobson (Airbatic) |
This instrument stuff is very interesting, but shouldn't it be in the avionics section? | ||
| tom ware (Tommie) |
anyone have proceedures for up grading flap and alieron control linkage pivot points ,to needle bearings from the orignal fiber type bearings? I had furnished larry olsen with the template for locating persise flight speed brakes,re:location on the skin. I'm not sure whom I got them from, jerry or the company .what I'm looking for is dim. and proceedures for installing them before wing close out. Also does anyone have the New improved enhanced cowl for IO540 i read about in the co. news letter some time ago? and are they happy? larry states it's still being reworked and is not available yet? |