BD-4 BUILDERS/OWNERS
NEWSLETTER

Issue 14, December 1986
(editors note: The publication date in the upper right corner of each page of the original is "MAY 87")

Dear BD-4 Builders and Owners,

A lot has happened since my last communication with you and I guess I am ready to talk about it. I had a bit of a problem with my BD-4 in June. I had been working on it to get it ready for the summer fly-ins and vacation. I had done a complete annual inspection and found nothing wrong. As always I had cleaned all the fuel sumps and screens and found nothing except a little very fine grit in the bottom of the gascolator. I was out of my biennial flight review so had arranged to do it with a friend. I took the plane up as usual to check it out and make sure everything was alright before letting anyone else go with me. I had a good time with low passes over the runway (we had an EAA fly-in going on at our airport), slow flight practice, and stalls. It really felt good to get everything going again! Later my friend arrived and we decided to get the BFR over with right away. The run-up was perfect and we accelerated to take-off speed. As usual I pulled the BD off at about 65 mph and pushed the nose over while I got the flaps off and built up speed to 120 which is best climb rate speed. I had about 800 ft left of the 3400 ft runway when the engine stopped dead. No misfire or sputter, just totally dead. I was about 20 ft off the ground, doing over 90 mph, no flaps, and it looked like no runway. I flipped the fuel selector to the other position as I was sure it was a fuel problem, verified full rich, pumped the throttle a couple of times and gave up. I forced the BD down on the last 30 ft of runway with brakes already locked and left two very skinny black lines as I just couldn't get any weight on the wheels. We have a 300 ft grass over-run on the runway and then it drops about 50 ft to a road and then 100 ft down into an area with a lot of trees. I always told myself that I would do whatever I could to avoid going over that edge. The braking action on the grass was lousy of course and I was still going over 70 mph so I knew that the gear had to go. I gave it full left rudder, and the BD yawed maybe only 30 degrees before the main gear box broke about 1 ft from the left side of the fuselage. The left side of the BD started to settle as the structure gave way and for some reason the airplane straightened out to almost runway heading. When it started digging dirt I noticed the left front side window shatter and thought it was because of the fuselage bending. Once the left front motor mount started digging I could see that our deceleration rate was just right so that we would stop easily before the end of the over-run. Once we started digging dirt we stopped in 100 ft. I calculated the deceleration forces and found them to be under 1 g.

We scrambled out of the right side door and except for having the shakes, we didn't even have a bruise. The only damage to the airplane was the main gear box, left and right side channels, and a bent prop. I was amazed to see that the left side channel was ripped in half where the left gear and 1 ft of the gear box had totally separated from the airplane. This means that the boxed in brace from the.spar to the lower left engine mount had to take all the forces from digging through the dirt and stopping us. It is bent back about one half inch at the motor mount and there is a resulting wrinkle where the bolt access hole is cut in it at the left side of the instrument panel. There was a small dent in the lower engine mount tube which is easily fixed. The carburetor was not damaged but the air box was bent some. The skin of the bottom of the cabin got a long rip in it when the gear box was pushed to the rear. The weirdest thing that happened is that the left front window was broken when the left landing gear rotated up and the wheel pant hit it and also put a large dent in the instrument panel. Scott DeGaynor had the same thing happen when he bellied his in.

Enough suspense - what caused the engine failure? I do not have finger strainers at the outlets of my wing tanks and someone pumped me a piece of junk big enough to plug the Flow Scan fuel transducer that I use with my Compu-cruise computer. I had it mounted under the cowl after the gascolator and a fuel filter but had trouble with bad readings probably as a result of some air or vapor lock in the transducer itself. I then mounted it under the instrument panel where the temperature and vibration are more controlled. The idea of using a Flow-Scan transducer rather than the one supplied with the Compu-Cruise was that it is supposed to be a full flow measuring system. I never really looked at the Flow-Scan but now I see that what looks like a large hole on the inlet side really tapers down to a very small hole inside the device. As it turns out the piece of crud that plugged it might also have plugged the top inlet to the gascolator. The answer to the whole problem is to put finger strainers in the fuel tanks or something like that. I can't get into that area now so I will be putting the see-through fuel filters in each of the tank outlet lines (4). I don't know whether they will be in the wing root or under the instrument panel.

I learned later that the FBO where I buy my gas had pumped several gallons of water to several customers about a week before my accident. They found and drained all affected aircraft so that solved the immediate problem. When they cleaned out the FBO tanks, they found that the fuel filters on the pumps had not been cleaned or changed for years. It would be hard to prove, but I think I now know where the crud came from. While at Oshkosh I bought one of the new funnels that filter the gas and separate out water. Gas will flow through the funnel at 6 gallons per minute and it seems to do a good job.

We talked about this at Oshkosh and it looks like less than half of the already built BD's have strainers in the fuel tanks. The idea is to have a coarse screen about 2 or more inches long in the tank and then let the gascolator and/or a fuel filter in the engine compartment catch the small stuff. In this way the small stuff will not slowly plug up the wing strainers. It would be nice if the wing strainers were easily removeable but I really don't thing it is necessary.

I haven't worked much on the airframe yet as we must finish the house first. It will be at Oshkosh 1988 for the 20 year celebration. In the meantime I bought half of a 1966 Piper Aztec recently so I do have something to fly - if only I find time to get my multi-engine rating.

BD-4 MEMORIAL DAY FLY-IN

Last year just by chance we had a fly-in at our place on Memorial Day. Somebody suggested it was the first annual event and everyone else agreed that it should be. Therefore, on Sunday, May 24, 1987 we will be celebrating the Second Annual BD-4 Day at Crest Airpark, Kent, WA. Crest Airpark has a newly surfaced runway, the trees at the south end of the runway have been removed along with some of the hill, and fifty feet of the trees along the west side of the runway have been removed. We live at the very northwest corner of the airpark at the end of taxi-way "A". You can just taxi right on down the hill and park in the large grassy area at the bottom or continue on up the hill to the west to our hangar (the big one) if there is room enough. If some would like to come earlier and pitch a tent for the night, please feel welcome. There is no restaurant on the field but you can borrow our car and go to the nearby shopping center.

We will be eating at about three in the afternoon. We will have a grill going so bring whatever meat you like to eat and the rest of the food will be pot-luck style. We will have a spare refrigerator available for keeping things cold.

Maybe we could have a spot landing contest as that seems to be one of the hardest things to do in the BD-4.

SUPER BD-4

As you know, everything is Texas has to be bigger and better and Ray Ward is trying to keep up with that philosophy. Ray now has his super BD flying and is very pleased with it. He is thinking of going to the CAFE 400 the 26-27 of June to see what it will do against the new plastic four placers. He is very excited about trying the tri-aviathon which is a new race in which each participant flies as fast as he can, as slow as he can, and best average climb rate up to 5000 ft.

Ray still has to do some fairing and such but is showing around 225 mph at 2000 ft and 3000 to 4000 ft/min climb rates.

The super BD is pretty standard except for an 18 inch streached fuselage, tubular Cessna gear, a new 300 hp 10-540 engine, and a three bladed prop. The empty weight is 1528 lbs and Ray admits to a little bit of lead in the tail to get the CG where he wants it.

We all will have to think about the BD-4 cooling problem some more as Ray is using the SX-300 cowling inlets which are no bigger than his inlets for his regular BD and he has been closing off the air outlet to get the cylinder temperature up where it belongs.

Ray says the airplane flies better than his other BD but is some harder to handle on the ground.

Ray also gave me a reminder about take-off in the BD with low fuel in the tanks. One of his early test flights resulted in a complete engine stoppage at about 500 ft. He had taken off with the fuel selector in a single tank position and had about 9 gallons of gas in that tank. The tremendous acceleration because of the 300 hp engine and probably steeper climb angle caused the front fuel line to unport which resulted in a loss of power. Ray switched the selector to both tanks and leveled off which allowed the engine to restart. Ray had changed the fuel system to incorporate the "rear tank feed line goes behind and under the door" method. He now has some other thoughts on ways to further improve the system. He believes that what he has is alright but the position of the "Y" where the lines from one tank become one is at the wrong place. He thinks that the system can be improved if the "Y" is placed at the bottom of the fuselage. He justifies this with figure 1, and explains it in this way: With aircraft sitting tail down, fuel level was checked with stick gauge (1) before flight. It shows fuel (about 9 gal) level at about (2). Throttle advanced wide open at 20 mph, aircraft accelerates to 120 in about 10 seconds. This figures to about 0.5 g acceleration (176 ft/sec/10 sec). One g is 32 ft/sec/sec as recalled from physics. The vector seems to show new fuel level (3) which not only uncovers fuel tank forward drain, but also the "T" where rear line joins. In a few seconds, air enters the "T" while acceleration causes fuel in lower line (4) to be drawn aft. Engine starves since no fuel is available from either line. I've thought of several fixes. (A) Placard the plane against take off with less than 1/3 tank. (B) Put in a header tank like my other BD-4. (C) Move "T" from position called out to position (5). If this is true, then it will solve the problem plaguing all BD-4s on steep pitch-up attitudes. I don't remember anyone proposing moving the "T", but it looks like a good idea for BD-4s. 
        Ray Ward

John Hartman, 38 Pinecrest Dr., Bedford, NH called me just after I got the letter from Ray and said that he was going to put to rest for once and all the question of the BD-4 fuel system. He is going to set up a jig with all the measurements correct and draw fuel through the system at about a 20 gallons per minute rate. He will then try different angles of attack and also the different fuel configurations proposed by different builders so as to determine a solution. I can't wait to see the results!

OSHKOSH 1986

Oshkosh was great as usual but a bit depressing for someone who had to go without his homebuilt. I arranged a "boondoggle" business trip to Baltimore for the end of Oshkosh week, got the airline tickets early because I was going on "vacation", and then went on the business trip a little early.

I never realized what a downer it is to have to travel to Oshkosh in a car (from Chicago yet). Traffic tie-ups where terrible even out in the middle of the country. You just have to visit a Chicago "over the freeway McDonalds" to get a good look at the common man. I am sure glad the EAA convention doesn't look that way!

Hugo Schneider's BD-4 forums went off very well as usual. A lot of the same things are discussed each year for the new builders and I have to admit some of the problems still aren't solved. Hugo also set up a talk in a regular forum tent which went over very well with several BD builders participating. Somehow I guess we all thought we were the only ones interested in the BD-4 anymore. Many people are still looking for a four place airplane that they can afford. Thanks to Chet Bartusiak for the photos of those of us who did some of the talking at the forum - next time we should comb our hair and put on suits and ties, don't you think?

I think that the "BD Award" has to go to the Texans this year for their nice finishes, interiors, and most progress" since last year.

EAA SUPPORT

John Brecker asked Ben Owen who is the Executive Director of Information Services for the EAA to communicate with me about BD-4 accident history. The EAA gets updates from the FAA for each type of 'airplane and the accidents it has been involved in. I have a list of all such accidents but it is not to be published. Most of the accidents were on early test flights and were either due to the quality of workmanship or pilot inexperience. A supprising number of new BD homebuilts seem to have so much twist in their wings that aileron can't overcome it. I have seen as high as three degrees of twist in one wing that flew without a problem. Some of these wings must really be twisted!

Ben Owen also sent a letter about the Homebuilder's Corner building. We can set up meetings there during the convention. This would be nice if we want some of the meetings at the convention site rather than at the university. Hugo, any ideas?

FOR SALE ITEMS

Gary Cook, 6713 Waxwing Way, Sacramento, CA 95842, 916-344-8318 has his project for sale. Fuselage is complete and on the gear but not skinned, instrument panel is in and IFR instruments are included. Controls are done but not in right now. The tail feathers are complete, and the wings are done (old panels). The seats have to be made yet. Engine mount for an 0-320 and cowl is included. Asking price is $5000.

LeRoy Hagel, Box 210, Towner, ND 58788, 701-537-5876 has his project for sale. The fuselage is ready for skinning and the wings are done. Has basic instrument group with some gyros but no radios. Comes with a zero time 10-360 with chrome sleeves. 89500 firm.

Don Holm, 151 S. Rhododendron Dr., Port Townsend, WA 98368, 206-3852171 has his BD-4 project for sale. Fuselage has been extended 18 inches and is ready for skinning. He has gear legs, wheels, brakes, tires, wing spars, extra center spar, most controls, firewall, tailwheel, and extra aluminum.

Charles Pinkerton, Rt.. 1, Box 83A, Somerset, WI 54025, 715-294-3459 would like to buy a constant speed prop for an 0-360 AIA and also a spinner. He would also buy just a set of blades for a Hartzel HC-C2YK-1B.

Dennis Brierton, 1520 Naperville Rd, Plainfield, IL 60544 815-4362539 would like to sell his flying BD-4. Engine is an 0-320 D2C using a fixed pitch prop (Sensenich 74" diameter and repitched to 56"). The performance is: Rotate at 80 mph, climb at 100 mph gives 800 to 900 ft/min, cruise is at 160 mph and top speed of 175 mph. Stall is 67 mph clean and 58 with full flaps. Empty weight is 1500 lbs. The airplane is being converted to a tri-cycle gear. Weight and balance will be done and a fresh annual signed off. It has wing tip strobes, 100 channel Genave Alpha 2008 Nav-Com and panel instruments are vacuum and electric. It has digital clock, flight time recorder, EST and many extras. Will sell complete and flyable or will part out.

William Baker, 4221 Indian River Rd., Virginia Beach, VA 23456, 804471-2579 is parting out his BD-4. The airplane was started in 1972 and completed in 1978. No accidents, always hangared, last flown Oct 1984, engine run-up and taxied regularly. Engine is a Lycoming IO-320 BlA with only 210 hours since major. Sensenich fixed prop with middle pitch. Electric fuel pump, engine mount. Fuselage and tail feathers with heathkit strobe and Hoskins strobe. Heavier main aluminum landing gear and larger Murphy nose gear and wheel. Wings with 4 cells of fuel in each (about 56 gal total) and landing and nav lights. Flight instruments, transponder, ELT, 100 channel Nav-Com. "Y" control column forward of control panel with chrome tubes through instrument panel and mahogany yokes with mike pushbuttons. Pants for gear. Total time airframe and engine is 210 hours.

MORE GASOLINE INFORMATION

Chuck Martel, 3375 Leawood Dr., Beavercreek, OH 45385 who works in the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson AFB, OH sent along some timely information about MoGas.

1. The mogas octane rating posted on pumps is often expressed as (R+M)/2, where R is the Research octane rating and M is the Motor octane rating. The octane ratings are measured using a single-cylinder engine with variable compression ratio and a variable fuel system so that the test gasoline can be directly compared to two "standard" gasolines of known octane rating. For the Research octane rating the engine is run at test conditions that simulate automobile operation at low speeds. The Motor octane rating is run at conditions that determine the knocking tendency of the gasoline at high speed conditions. Of the two octane ratings determined for a motor gasoline the Research rating is the higher of the two rating values, often 8 to 10 numbers higher than the Motor rating. For an unleaded regular gasoline with a minimum (R+M)/2 rating of 87, the Research rating may be about 92 and the Motor rating about 82.
2. The Motor octane rating method for motor gasoline is very similar to the Aviatrion octane rating method. (For a Grade 80 aviation gasoline (80/87), the lower value (80) is measured using the Aviation octane rating method and the higher value (87) is measured using the Supercharge rating method. The Aviation rating is a measure of the knock resistance of the gasoline under lean, cruise conditions. The Supercharge method is a measure of the knock resistance under rich, full power conditions. The Motor octane rating method for mogas just happens to be very similar to the Aviation octane rating method for aviation gasoline (avgas). A rough estimate is that a gasoline with an Aviation rating of 80 would have an 80.5 Motor octane rating.
3. Motor gasoline is normally produced to the American Society of Testing and Materials (ASTM) specification D 439. An unleaded gasoline that meets this specification will have a minimum Motor octane rating of 82; this exceeds the minimum Aviation octane rating for a Grade 80 (80/87) aviation gasoline. A nationwide survey conducted for the Department of Energy in 1983-84 revealed only one area in the US where the Motor octane rating of unleaded regular was not in excess of 80.5. This sample was from the western plateau area where the high elevation permits a reduction in motor gasoline octane rating. (High altitude reduces the manifold pressure which reduces the engine power, and this reduces octane requirement.)
4. This same survey compared the properties of unleaded premium gasoline with unleaded regular. Essentially the only difference in the two grades was in the octane rating. (However, since then I have read that some of the premium motor gasolines produced today have an increased amount of detergents and other additives to reduce fuel injectin nozzle fouling problems.)
5. The hazards of mixing jet fuel with gasoline have been well publicized, as the end result is often a fatal accident occurring shortly after takeoff. Tests run several years ago showed that 1 % (by volume) jet fuel added to Grade 100 aviation gasoline reduced the rich performance octane rating by over 5 numbers. You can imagine what the octane rating of a 50/50 mixture must be.

Chuck bought a partially built BD-4 from Carl Rorabach of Latrobe, PA in Nov 1985. Since then he has built the vertical fin, rudder, and horizontal stabilator. He is converting the fuselage from tri-gear to taildragger. He says that there is a lot more to say about fuels and he will give us some more at a later time.

Thanks for sending the article Chuck.        rdm

MORE FUEL FLOW INFORMATION

by
John Brecher, Nov. 1986

I'm getting down to final assembly now. I'll be taking the BD to the airport next weekend. There I should have 3 or 4 weeks of readying for flight test. Tinsman is to do the test flying and he is having some knee surgery next week so plane and test pilot should be ready by mid Dec.

I just went through a month of Avemco, EAA, and chapter designee drill trying to get insurance coverage. I knew there had been some problems with fuel starvation but didn't know the magnitude. Avemco says they insured 9 BD-4's before my request and all 9 crashed with what they felt was a fuel flow problem. Avemco asked me to contact Ben Owen at EAA headquarters to discuss my fuel system. I told Owen that I had run the fuel lines down the front and rear door posts like Cessna. He asked that I call a local designee for a visit. I got Jim Miller from Chapter 91 in Kansas City to come and look over my system. Miller, Tinsman, and I went over everything. Miller got to the point where the two lines from each wing "T" together. He felt this was totally unacceptable. He was sure the air from an unported line could win out over fuel flow, particularly with just a "right" or "left" fuel selector. Tinsman and I argued that most BD's were plumbed that way. Miller also didn't like the rear fuel pickup running forward to just 3 inches from the front pickup. He felt that would cause head pressure difference to be very low and thus allowing air in the system.

First, Miller suggested a "flop tube" and one line per wing. I also said I wanted to make a "both" position as per Jim Kerr's letter in BD-4 newsletter in the mid 70's. Miller agreed. The flop tube could get into the fuel sender unit but naturally I thought of that after Miller had machined two "work of art" rolling flop tubes at a cost of $100.00.

I told Miller I'd heard that the insurance company would accept a BD-4 if it had a header tank. I didn't want to put it under the panel as that would be difficult with the panel complete. I suggested a pair of tanks behing the seat would be easier and better for weight and balance. Jim said that would work fine. We came up with the size due to Wickes tube size available 4 inches in diameter and 20 inches tall fits nicely. This holds 5 quarts each tank.

Miller feels very strongly that this mod will cure the fuel flow problem and thinks it should be mandatory. Tinsman and I feel there are other fixes too. I think the both position is a major factor. The system the fellow in PA did with outboard bay sumps is good.

The fuel selector mod takes less than one hour and costs nothing.I'd like to know if any BD had fuel flow problems with the both selector.

Miller is sending the attached article to EAA for publication.

I installed the system as drawn. It would take someone about a weekend to retrofit at a cost of almost $120.00. Miller welded up the tanks from 6061-T6 tubing. Nylo-seal was used from bulkhead at wing to the fuel selector. As I've said, this is a good fix, but not the only one.It is going to get me insured with Avemco. Rates with me having 300 hours logged is:
Liability - 500,000 each accident, 50,000 each person = $540.00
Ground and Taxi - 16,000 value = $824.00
Liability, ground, and in flight = $2603.00 !..

At meetings I've gotten the impression that insurance doesn't rate very high with others but it does with me.

John Brecher, BD-4 N-186JB

The following letter was sent to the EAA.

BD-4 FUEL FLOW PROBLEMS

The BD-4 Aircraft has apparently earned a reputation for fuel flow problems. One insurance company reports that 100 % of the BD-4 aircraft that they have insured have been damaged as a result of fuel flow problems. Consequently, this insurance company will not insure a BD-4 with the original design fuel system. After being refused insurance, a local builder sought assistance in evaluating his fuel system. This article is the result of that evaluation.

The BD-4 utilizes fiberglass wing cells for fuel tanks, with the majority of the fuel space being located behind the tubular spar. Feed lines from each tank port join together near the fuel selector valve that is located below the instrument panel. The fuel selector valve has 3 positions: Right Tank, Left Tank, and Off.

This arrangement appears prone to experience fuel flow problems with anything less than a full fuel load, because one port can be uncovered during high angle of attack operations. The uncovered port then allows air to enter the line, near the selector valve, and reach the carburetor or fuel pump, resulting in complete loss of power.

Secondly, the lack of a "both" position at the fuel selector valve subjects the aircraft to total loss of fuel flow in a slightly uncoordinated or climbing turn if fuel is being drawn from the tank in the lower wing. The obvious solution for the fuel selector valve is to modify it to provide a "both tanks" position or, to obtain a valve incorporating this provision. It is also important to placard the aircraft for use of the "both tanks" position during take-off and landing operations.

On the specific aircraft that was the basis of this article, the unported tank outlets that occur during high or low angle of attack operations were accomodated by installing a pair of 5 quart header tanks behind the rear seat. Each wing tank port feeds directly into the associated header tank via an individual 3/8" minimum diameter line. Each tank port is protected by a finger strainer. A balancing line to each header tank was installed. This is absolutely necessary to avoid an air locked condition and insure rapid refill of the header tank when normal aircraft attitude is resumed. The normal main tank vents must not be directly connected to this balancing line.

The header tanks were constructed of 20 inch lengths of 4 inch diameter 6061-T6 tube with 0.050 inch walls. The tanks were located vertically just aft of the rear seat with the lower end secured to the aircraft's lower skin via the drain valve fitting. The upper end was secured to the seatback frame. Fuel is fed to the selector valve at a point one inch above the bottom of each tank. This provides a sump for water collection and removal. The general arrangement is as shown in the drawing. Total empty weight addition was approximately 4 pounds for both the header tanks and the additional lines.

The positive aspects of these changes are that the header tanks not only add 2 1/2 gallons of additional fuel, but also allow reliable use of almost all fuel on board. Take-off acceleration forces will tend to insure that the header tanks are full. Also, full header tanks will provide at least 10 to 15 minutes of usable fuel after almost every drop of fuel is used from the wing tanks.

The changes described appear to overcome the problems inherent with the original BD-4 system. It is suggested that equivalent changes be considered manditory modifications for all BD-4 aircraft (see Figure 2)

Jim Miller, EAA Technical Counselor #529

There is merit to the above fuel fix. I guess the fuel in the cockpit bothers me some, but it is in a better place than under the instrument panel. 1 think that a single tank would be much better than two as far as complexity and probably weight.

The thing that really bothers me is sending such a letter to the EAA and claiming that it should be mandatory on all BD-4's. When this was sent, there had been no physical testing of any sort done to prove his theory.

Avemco's story bothers me also in that I have called several times over the past 5 years and they always say that they cannot cover BD-4s because the flaps and ailerons rip off in flight!

Click on image for larger view

HELP ON THE NEWSLETTER

Due to all the work I have ahead of me, I asked Paul Kauffman, 3625 Holliday Village, Traverse City MI 49684, 616-938-9152 to give me a hand. Paul is very dedicated to the BD-4 and knows all of it's history. He will accept letters and phone calls for help and will answer them with letters or in the newsletter. I will still be here and will talk to anyone and will put the final newsletter together and have it printed and mailed. We are both hopeful that many of you will send stories and how-to articles to include in the newsletter!

DUES

If you do not have a a sign in front of you name on the mailing label, you owe $5.00 if you want to continue with the newsletter. The fund is in very good shape for the next 3 or so letters to those who have subscribed.