December 1982 - American Bonanza Society

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Colvin's Corner J . Norman Colvin Retired Beech Project Engineer on Bonanzas and Barons ABS Technical Consultant Service Ctinic tnspector 35'S SLOW FLAP OPERATION Dear Norm: The flap motor on my Straight 35, S I N 0· 13 13 , has developed a " flat" spot (or so I'm told), and it is in need of replacement/ repair. Considering the extremely long extension and retraction time of this model, is it possible to install a flap motor which will decrease these extension and retraction times It so, what is involved What is the cost T. M. Sullivan ASS # 11 590 ELECTRICAL PROBLEMS - V-35B Oear Norm: I have a 1977 V-35S, S I N 10063, with a few cranky electrical problems. 1) In the August issue there was a discussion of a repair to a G-33 subpanel lighting system. Is my system the same I have replaced the transistor and potentiometer. Occasionally I when rheostat is run all lhe way up, the panel will lighl up briefly lhen go out. If th e sysl em is the same 400 cycle, should I replace the inverter next 2) The tesl circuit of the three green position lights fails to light ri ght main gear light, yet when the gear is put down all is green. Should I suspect th e right gear-down position switch Does it have dual pOints, one for down position and one for up (test position) 3) Left fuel gauge often fails to indicate. In analyzing the circuit I understand th e two sending units " leak" a smaller or greater amount of current to ground (they are in series), thereby giving the graduated mading. (When inboard sender is disconnected gauge deflection is severe·to-full.) I have checked contacts on back of the gauge and at fu se buss. Should I suspect a bad gauge 4) Right fuel gauge upon reaching 1/ 2 to 5 / 8 begins to flick to full sharply until gauge reading gets below 1/ 2, then it settles down. I suspect poor winding contact on one of the two sending units. The inboard unit was replaced under warranty for the same problem and was okay for about a year. Should I zero in on the inboard gauge again These little electrical problems are very annoying, and I would like your comments before I start replacing parts on a trial / error basis. 5) Grease level in gearbox - I seem to remember many issues ago a discussion of grease leakage due to overfilling. At our last annual my IA said the box required grease. Since then grease is leaking through the belly drain holes. Yet, a careful inspection of the bottom seal shows no seepage at all. Is there a seal at both the motor mounting and the hand crank shaft I have lowered my main struts due to removing the step. Could that cause the box grease to leak out of the crank seal or a vent hole if it is overfilled Enjoy your column very much - keep up the good work. Roy N. Foxworthy ASS # 41 34 Dear Mr. Foxworthy: The most logical source of trouble in the panel lighting system is the inverter. It should be replaced. The inverter most likely is producing too much power, thus blowing a transistor in the system. The landing gear test circuit most likely has a blown diode since th e trouble seems confined to the test circuit. Yes, the circuit has dual points. The most logical source of trouble in your fuel gauging circuit is th e printed circuit board. These PC boards are located above the fuel gauges and att ach to the instrument panel flange. If only one tank is giving trouble, switch PC board s to see if the trouble moves. PC boards have been improved, so new boards should be more reliable. When landing gear gearboxes are overfilled with grease the surplus grease works oul the emergency gear handle seal. Due to overfilling there also may be some leakage out the vent hole on the top side of the gearbox. Fluid level in the gearbox should only be high enough for the worm gear to pick up lubricant. This can be observed through the filler hole. Only correct lubricant (Mobile #626) should be used in th e gearbox. The gearbox spline shaft which runs through th e gearbox is sealed at top and bottom by Garlock seals. Any leak at these pOints would be unusual and obvious. If the seals are leaking, seal replacement would be necessary. It appears that your trouble is a simple case of overfilling, and I would Question with what kind of grease. Strut inflation has nothing to do with the leakage. Dear Mr. Sullivan: The flap motor in your Bonanza is considerably different than in later-model Bonanzas, so there is nothing that can be done to speed up flap movement. It wouldn't hurt to check the electrical circuit for high resistance; but on your model Bonanza, flap speed is just slow. SOUND INSULATION FOR ENGINE COWLING Dear Norm: I have two items for discussion! In the May , 1982 issue you wrote to apply " Vaporite 550" for insulation. The product is manufactured by the Anderson Pritchard Oil Company. I called Beechcraft West; and, after calling the factory, th ey advise me it is not available. Would you please give me an address for Pritchard I have another supplier who may be able to obtain it for me. What else would you recommend be applied to the underside of th e cowling for noise reduction I have been reading aboul the importance of keeping the gyro pressure pump inline filter clean. Mine turns black in 25 hours use (V·35A). I get the feeling the pump is wearing rapidly. Is this normal The ASS Newsletters are fantasti c! I praise and tell every Bonanza owner I meet to join. Stanley C. Meyer ASS "'3001 Dear Mr. Meyer: Vaporite 500 would not be good malerial for the underside of the engine cowl. Engine heat might cause it to melt. I feel it would be a waste of time to insulate the cowl since that does not cause noise in th e cabin. If the cowl doors were to be insulated, I would use Scotch Foam Y·370, which is a 3M product. The bulk of noise in the cabin comes through the windshield and side windows. Some noise comes through the side fuselage skin between the firewall and door post. page 1268 american bonanza society
• • It sounds as if your instrument air pump is wearing. It is important to use th e new pleated-type instrument induction air filter and to replace the inline filter on a regular basis. It helps to install an air blast tube to cool the pump . The pump vanes are made of carbon and run dry and hot, so they do sluff off. The black you see is on the pressure relief valve and is norm al. H-35 CABIN NOISE LEVEL Dear Norm : l awn a 1957 H-35 Bonanza. The engine noise level in the cabin is very high, especially when compared to the S and later model Bonanzas which I fly regularly . New mufflers and Beryl D'Shannon exhaust pipe extenders have not improved the situation appreciably. Even the exhaust manifold gaskets were replaced to no avail. Could you please advise as to wh at type of soundproofing materials could be used, along with installation instructions and where in the air frame soundproofing would be most effecti ve Ron Saglimbene ABS # 13335 Dear Mr. Saglimbene: The primary source of cabin noise comes through the windshield and side cabin windows. Replacing the windshield and windows with thicker glass is th e easiest way to lower noise level. 3M Products makes a sound deadener called, ·'Scotch Foam Y-370··. This is a self-adhesive foam in sheet form . GT Sales and Manufacturing at 220 2 South West Street, Wichita, Kansas 67203, 3 16 / 943-2171 , stocks this material along with other sound deadeners. The firewall and cabin side panels forward of the firewall require the most deadener. The belly skins below the floorboard s take a black spray-on sound deadener; however, factory installed material in this area should be adequate. Be sure the exhaust stacks clear the fuselage structure in the cowl flap well. And , remember, in cruise the engine cants to the left about 3 / 8 inch . Skin canning in flight can make a terrible noise, so be sure that somethIng other than normal engine and propeller sound is not contributing to cabin sound. SECOND INSTRUMENT PUMP ADDITION TO DEBONAIR Dear Norm: I have a few questions concerning our 1960 Debonair (CD-1 20): 1) Is it possible to install a second vacuum pump on the spare accessory pad on the 10-470 I want to have this pump drive a second and separate horizon rather than tie it into th e existing horizon. An y ideas 2) Both main fuel gauges show full when the tanks are full , but after using either tank for a short period (20 - 30 min) the indicator goes down to 1/ 2 to 1/ 4. Cycling the gauge selector switch from left to right sometimes helps, but not usually . 3) I would like to replace the existing mixture control to a vernier type and need to know where to get one. Al so , how long is the cable - as I see them adverti sed with varying cable lengths 4) Where can I get a copy of the book, " Those Incomparable Bonanzas" S. P. Simpson ABS # 15346 Dear Mr. Simpson : I can see no reason why a second pump could not be added. At the moment, I do not know of such an installation; so you would have to work out th e plumbing details (which should not be a big deal) and either obtain an STC approval or obtain a one-time FAA approval. You can purchase a throttle vernier control from any Beechcraft dealer. I think Part # 35-944046-1, which fits a Model M-35 Bonanza, will work. I do not have access to cable lengths. Write to Larry Ball , 8529 Chapel Glen Drive, Indianapolis, Indiana 46234, to request one of his books. VACUUM PUMP FAILURES Dear Norm: During the past several months, there have been many articles in various trade publications regarding vacuum pump failure during IFR fli ght. I'm now a " nervous believer". I would like to install a vacuum failure warning light or horn on an F-35, but our local Beech facility does not know how to proceed. To your knowledge, can this be accomplished D. W. Wennberg AB S # 11 64 3 Dear Mr. Wennberg: This is in reply to your letter in which you talked about vacuum pumps. I think that most of the talk you have been hearing about instrument air pump failures are related to the dry instrument air pressu re pumps. Your instrument air pump is a wet vacuum pump which is intern ally lubricated and will norm ally run trouble free between engine overhauls. Like anything mechanical there is always the possibility of failure but from past service experience, it is remote. A light or horn could be hooked into the system, by installing a pressure switch, but pressure switches give trouble, too and I really believe they would not accomplish what you want, because when pumps fail , the drive shaft shears and the pump stops without warning. I feel that your fears are unfounded. Just be sure that the vacuum pump is overh auled at engine overhaul. Thank you for writing. FUEL VENT SYSTEM IN A TRAVEL AIR Dear Norm: I have read several incidents recently on problems with the Bonanza fu el venting tubes. Since my Travel Air is very similar to a Bonanza in many aspects, I am concerned that the fuel venting tu bes are not positioned in the proper angle nor extend from the base of the wing the proper length to give proper venting per article, " Damage to Venting System", page 1243, October Newsletter). Nowhere in either my maintenance or parts manual are there any indications on the length or angle that these vent tu bes should take. If there is any inform ation you can provide me, I would appreciate it very much. Clifton M. Buell ABS # 14983 Dear Mr. Buell: Fuel vents in your Travel Air should protrude below the wing or fuselage one-and-three-quarter inches and should be bent forward ten degrees . The end of the tube should be champhered at 45 degrees. Vent tubes have a small ice-free vent hole drilled through the back side of the vent tube. When bending th e vent, always bend the tube below this vent hole. It is a good idea to occasionally apply low pressure air to the vent tubes to be sure they are free of internal obstructions. Always remove the fuel caps before applying compressed air to the vent tubes. OIL COOLER ON MODEL 35 BONANZA Dear Norm: I have a question regarding repair (or rebuilding) of the E-series oil radiator used on SI N 0-11 17 and later. Since Beech can no longer supply this part, I am wondering if you could put us in touch with the original manufacturer. I would like to obtain a new radiator only (not inc luding tank) for welding into our existing tank. We have a leak at present involving only one of the radiator tubes. It is a simple-enough matter to plug oft one or two tubes: however, if one tube is corroded through, several others may not be far from failing. Our problem is not urgent. This is a spare tank which we purchased several years ago as part of a run out E-225. The leak was not discovered until 1 american bonanza society page 1269
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December 1982 - American Bonanza Society

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