April 1993 - American Bonanza Society

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I Q I M35 oil filter. My corporalion is now the proud owner of 'I9860R, a 1960 M35 Bonanza. This is Ill)' first Bonanza so I have several questio ns for you. The 10-470 e ngine has an oil screen. I have seen that there is a kit available to replace the oil screen with a fil ter. Do you think this conversion is wOl1hwhile? Also. I have noticed a discrepancy in the Beech owner's manual and the Continental engine manual. The Beech manual says to change the o il every 50 hours whjJe the Continental ma nual says evclY 25 hours. How often should I change the oil? -David N. Schach, ABS 28861, San Fmncisco, Calif. rpm, OAT was 12 C (ISA+ 19); lcanedlo 20 degrees rich of peak, the CHT sr.,yed pegged al 200 C. Other examples are, al 4,000 ft., OAT 24 C (ISM 17) 23/2300, 20 degrees rich, CHT pushing 225 C, so cowl flaps were opened, al 9,000 feet OAT 16 C (ISA + 19) full lhrotlle (20.8 inches) 2400. 20 degrees rich, CHT 200 C cowl flaps closed . I am very meticulous in the operation and service of lhis aircraft, as any !>afc pilot/owner should be. I alway~ felt that g(xxi maintenance and operation according to the POH would get this engine to TBO. Now I am con- ] . Norman Colvin, retired Beech cerned thal excess heat translates to Project Engineer on Bonanzas excess wear. and Baro ns, AmcriGIn Bo nanza My question is, will a holter operat- Society's Technical Consulwnt ing engine (e.g. 200 C) wear faster than It's best to change oil at 25 a n dSe rvi ~e C Ii~k. l ns~LO r and an engine that opemtes in the 150 C to ~ A hour intervals if the engine autho r of ColL'm s ClJmc. 175 C range or is the difference neglidoes 11.01 have the o il filter gible? Secondly, do you believe the and 50 hours if it does have a filter.You Can pur- excess oil consumptio n is re lated to the hotter running chase dle oil filter ada pier for your engine from Warren tempera lures' -john F. SCianillo, _NID.. ABS 19181 , Fort James, phone 619/ 438-9590. Lauderdale, Fla. \Vhen this adapte r is installed, the o il screen can be removed and whoever installs the adapter must be sure that four or five thread contact w ith the e ngine is obtained. When you talk to \Varren James, ask what the lock nut torque value is. 10.5508 cylinder head temperatures. You have ~ Q probably seen the Beechcraft SelVice Comlllunicalion (No. 91, daled May 1992) regarding high CI-IT's on the 10-550B engine. I own a 1988 A36, SIN 2421 wilh 770 hours and r would like 10 share my obsclVations for your conunents or suggestions. I have noted all along, since acquiring this aircraft, that the CHT would rise close to the red line on climbout requiring lowering of the nose. You just can't climb out at Vy and keep dle CHT below 238 C (Red Line). 1 expressed concern about this to several mechanics and was led to believe d1at Ihe 10-550B nonllally ran hol. The only suggestion I received was to usc Mobil AV-I ($8.00/ quart) because it could w ithstand these hotter operating temperatures. Along with the honer CHT temperatures, I have been experiencing increased oil consumption of one quart evelY 3.5 hours. No I",,,k can be found bUllhe breadler lube drips a few dro ps. I found the oil dipstick had vibrated loose on one occasio n and re placed the gasket but it hasn't helped. There is an interesting quirk when leaning this e ngine. If leaned 10 20 degrees lean of peak EGT. Ihe CHT wi ll cool down to 175 C, whe reas at 20 degrees rich of f'C'"k the CHT is pegged at 200 C. Most mechanic') do not have an explanatio n for this and some don't be lieve it, but my guess is that unburned air is cooler than unburned fuel. I fl y in the southeast, based in Fort Lauderdale. On a typical trip at 11 ,000 feel M.P. of 19" (h,Jlthrottle) and 2400 I AA I The 10 -550B engine had a cooling problem, however, Ihis problem can be solved b)' calling Turbo Flight, phone 303/731-2127. These people have obtained STC approval for new engine baffles that really correct the problem. r would suggest that you add a second gaskel lO Ihe oil dip stick cover. Unless this cover is tight, it will allow air to enter the crankcase, pressulizing the case, which forces oil Ollt the engine breather nlbe. It wouldn't hurt 10 boroscope the c:ylindcrs to check for their condition. The engine is using more o il than n0 I111al. It is possible that the cylinder walls have rust spots. \Vhcn you lean the engine o n the lea n side of best power, the engine develops less (X>wer. so less heat is generared, CHT cools down. You are right, excessive hear contributes to premature wear and shorter engine life. I would suggest that you get light on the baffle change, since it definitely wi ll solve your problem. Fuel mixture problems. I have a 1966 C33A Bonanza and I am havi ng trouble with the e ngine ~ Q running rough when the mixture is enriched on descent. \X1he n descending from altitude, me engine begins to run rough when the mixture is put in too far. At about 2,000 feet we have to leavc the lnixture about one to one and a half inches out. Full rich at this altirude causes the engine lO run rough. \VIe have been leaving the mixture out this far, or perhaps a little less, all the way to the ground. Then, on rollout, we have had trouble with the engine dying wh ile it is at idle. Lately. we have had to increase the throttle until the rpm is 1000 to prevent rhe motor from dying on roHouL In servicing the syslem, we decreased the mixture until • COLVIN'S CORNER AMERICAN BONANZA SOCIETY, APRIL 1993 PAGE 3199
, we obrained a 25 rpm increase at shutdown. (111e mL\.'tUre has been decreased as much as possible, i.e .. it C""dnnOl be physically decreased any more.) Previously, it was about 70 rpm at shutdown. This adjustment seemed to have no effect on our problem. We dlen tested the fuel pressure. Idle pressure was approximately six to seven pounds. -nle high pressure was adjusted down to 29-30 pounds. Once again, these adjustments seem to have had no effect. Hot days are probably worse than cold days. I have looked through the owner's manual but I have not found much information abollt proper ~Idjllstment of the mixture on a descenl. At about what altitude should r be able to make the mixture fu ll rich? The engine (10-52013) has approximately 570 hours SMOH. The airplane just went through its annual inspection. All the spark plugs were cleaned and the worn ones were replaced. Compression was good in all cylinders (70+). Do you have any suggestions on how to ftx our problems? -ROil D. \vinter, ABS 25999, San Mateo, Calif. Here are things you should check The throttle ann and a short metering anll are on the same throttle shaft. Open the throttle one-third of the way open, then hold the metering ann and try to move the Lhrotrle ann. The rwo anns should move together. There should nor be any appreciable amount of wear in the linkage berween the fuel metering ann and li nkage. Check the vent ho le in the cap on the manifold valve. There should nOt be any fuel stains around the hole. I would guess that you have the bracket sponge induction air filter. On a quiet clay, remove this fi lter and go ny the airplane. If this corrects the problem. replace the filler with the pleated flIter. When you are at, say, JO.OOO feet and start to let down, reduce rpm but don:t touch the mixture until pattern altitude, then go full rich, unless pressure altinlde dictmes differently. My guess is the trouble is in the induction air filler. One more thing to check is the alternate air door. Be sure it has good spring tension. I feel sure that one of dle above checks will correct the problem. If not, let me know. I Q I Fuel mixture problems. I have a question regarding EGT method of mixture control. [ have a single probe EGT and I lean to 50 F rich of peak at 6; percent power. The fuel pressure at this setting is considerably lower than the 65 pe rcent range on the fuel pressure gauge. Typically at 50 F rich of peak the fuel pressure is around ;.5 psi at 6,500 feet rather than the book value of 6.6 psi. Is this something to be concerned about? Should I keep the fuel pressure in the 65 percent rdnge regardless of EGT' I do average about 12 gaVhr leaning to 50 F rich of peak. Secondly, I've noticed, or at least perceived, an increase in engine vibration. Engine temperatures and pressures all remain nonnal and I have nO( noticed any decrease in available power. It JUSt seems to vibrate more and appe ~lrs more p revalent at higher rpms. I just changed the oil and, as I do at every o il change, sent a sample to be analyzed. I don't have [he resuils yet. Is there some diagnostic test that can be done to determine the cause of this vibration? It would help my peace of mind to know. The engine has about 650 hours SMOH. I believe the crankshaft is original and that would mean it has about 3400 hours. I"ve pulled the prop through and did not feel any cylinder to be completely flat. Mag checks are good. Oil consumption is still around one quart eve!), 10 hours. TIle Beech prop inspection \vas just done--no cracks. Could these two questions be related? In other words could T be over-leaning' -Bill de Gm/), ABS 26789, Ridgecrest, Calif. Since there is room for error in both me EGT and ~ A fuel pressure gauger I would like to start with basics and check for the unmetered fuel pump pressure. To do thiS, a fuel line should be teed into the fuel line between the engine driven fuel pump and the fuel metering valve. A fuel pressure gauge should be hooked to the teed line. At 550 to 600 rpm, fuel pressure on this gauge should be 9-11 psi and at full static. should be 25-27.5. ext, check idle mixture. \'\Iith engine idling at 550 to 600 rpm, pull out on mixture control until the engine quits, however, just before it quits, the tachometer hand should jump 25 rpm. With the basic information calibrated then it is a matter of testing the fuel pressure gauge for accuracy. If this proves OK, then check the EGT probe. I'm nor Sllre, but 12 gallons an hour seems a bit lean. I just am not sure. For engine vibration, check right hand exhaust tailpipe for clearance, where it exits the nacelle at the cowl flap opening. You should have three-forths inch clearance. Next use a flashl ight and look up the exhaust tailpipes to see the flame cones inside the mumers. The flame cones should be centered inside the muffiers. If not. the)' have broken loose causing roughness. Check the hose that connects the two induction air balance tubes. TIlis hose is directly in front of the engine, so it is hard to see. It wouldn't hurt to check the engine mounts for condition. I wouldn't rule out over-leaning, not beGluse of what you a re doing, but possibly bc(:ause of fuel pump unmetered pressures. If this persists. let me know. Bonanza rig problems. Thank )'ou for ),our help ~ Q with my undercaniage problem recently. Your letter, the sight of the relevanr pamgrdph in your book and the great improvement that a new bolt and bush make has satisfied my engineer that it is OK. Certainly the movement in this joint is now quite small. Whi le completing d,e airfmme check, my engineers had to adjust the small trim tab cables, as they were below tension, to the port side and they tell me they adjusted each cable by an equal amount. However, when I next flew. T noticed that the trim wheel needed to be almost at its full nose down position to maintain level flight at 75 percem power at 3,500 feet and a good amount of left rudder \vas needed to keep the ball in the center. To correct this, they adjusted tJle other trim tab up one degree and the side slipping problem was solved, but she still needed t.he trim set at three degrees nose down for the cnlisc with just myself and wife on board and the center of AMERICAN BONANZA SOCIETY, APRIL 1993 PAGE 3200
Page 2 and 3: I IN THIS ISSUE I COVER. Spirit of
Page 4 and 5: BONANZA OF THE MONTH ; Round-the-Wo
Page 8 and 9: gravity near the forward limit. To
Page 10 and 11: AD! L26000 Louis H. Abbett L7978 Br
Page 12 and 13: How to buy a used bird By George Wi
Page 14 and 15: Thanks for Orlando BPPP. [ just wan
Page 16 and 17: them up for bench testing. They che
Page 18 and 19: Replacement value? Consult d1e Blue
Page 20: APRIL 16-18 · Bonanza Pilot Profic

April 1993 - American Bonanza Society

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