Paul Sharp replied
Here are three items of input for what they're worth:
1 - You must fly for about one hour on the main tanks BEFORE using the aux. tanks because unused fuel will return into the main tanks, so I think you have it right when you put "after one hour on the main tanks." If they are full (that is, you haven't flown on the main tanks to use some of the fuel), then the unused fuel trying to get into them from the aux. tank usage will vent overboard, being wasted.
2 - I can fly on my aux tanks for 1 and 1/2 hours at 65% power settings. When the engines start to miss, I switch back to the main tanks. Often I will cycle the fuel pumps on while getting the full flow back after running the aux. tanks down, depending on whether I switched immediately or took a few seconds doing it. Of course, once the engines even out I turn off the fuel pumps.
3 - After landing, I usually have the linemen put 3 gals. each into the aux. tanks so that there is some fuel there to keep the bladders from getting dried out. That way I know what kind of fuel weight is involved (18 lbs. each side), but have the option of not using the aux. tanks when I want to fill the plane with more weight (either passengers or cargo).
Dave Zavoina added
There is no reason to put any gas in the aux tanks because they are aluminum, not bladder type. If you are going to put fuel in the tanks, they should be topped to keep out condensation. I has numerous pinhole leaks in mine when I got it as a result of moisture being left in the tanks.
Paul Sharp then asked
Are the mains aluminum also, or are they bladders? I just went by what a mechanic told me about the tanks being bladders. If that's the case then I won't put any in the aux. tanks.
Dave Zavoina replied
Yes, the main tanks are aluminum also. CE-337's thru 337F's have two tanks per side, mainfolded together and feed the sump in the lower foreward boom (where the sump drain valve is located). G and H models are manifolded along with the early model aux tanks, to form the mains, unles they have the long range tanks, then they would have a fourth, smaller tank, outboard, still all manifolded together.
Paul Sharp replied
I have no TIT gauges on my 1967 T337B. And the EGT gauges are merely relative - I use them to determine the peak for a given altitude and settings.
Add to those two items the thinking I use that saving money is relative in the sense that getting there 5 to 10 minutes sooner for each hour of flight saves money just as surely as flying longer at lower settings - and this is a subject on which you'll get many an argument pro and con - but the last article I read in one of the flying rags concluded that flying at 75% is actually more economical than flying at 55% in the long run, etc.
With the above in mind, here's how I set it. My initial climb settings are reduced to book figures after takeoff: 2800 inches and 2600 RPM. When I reach my normal cruising altitude, which for my short weekly flights is around 10,000 feet, I reduce the manifold pressure to 27 inches, which makes for a 75% power setting at a nominal 10,000 feet. If I go higher, then I use the settings in the book for 75% at that altitude. Then I peak the fuel mixture setting using the EGT gauges and enrich until I get 125 degrees below peak.
Until a couple of weeks ago I was enriching for 75 degrees rich of peak, but the club response on this site suggested that 125 degrees will result in longer engine life, so I've been trying to do that. I've noticed a considerable difference in fuel flow readings between the rear and front engines to get that kind of setting, but figure the setting from the EGT peak/enrichen process is probably more accurate than the fuel flow meters. Maybe other readers can throw in some comments that will illuminate this subject more.
I also have begun to do my takeoffs (on normal, long paved runways at the larger airports where I fly most, that is) with no more than 28" MAP. That's also due to input I read here from the "club" suggesting that keeping the Turbo models limited to that setting will result in longer life.
G.M> 337 Skymasters Club added
EGT and TIT are two of the same... if you use the EGT for controling the fire... how would you change the TIT?... would they not be the same as they are in the same pipe... if we analize the system.. we would find that the turbine inlet temp should really be lower than the EGT for it is further away from the exhaust valve... so I think I would use the EGT for my setting...
As far as the power setting... it depends on what speed and power setting you want to use. I would use anything between 2600-2300 rpm and a Mp of less than 28 inches.. to keep it in cruse configuration... most are running around 55-75% power... and it seems to be a nice setting for everything.. engine life, fuel... etc.. As each of the airplanes have changed in years the settings will be somewhat different. To use anothers settings would only be a guideline... as the previous reply is the correct way to set your engine up.. for cruse flight after getting 75% powere or below...
To extend your range... by leaning further... is possiable but, I would only do it when needed... as it does seem to shorten the life of the engine If I were running out of gas and the range and endurance is what I needed to be safe... you be I would lean out to peak.. but, then again I would be down around 40% power...too... it does you no good to save the engine and crash the plane because you run out of fuel.. then again I would think that pre-flight planing is in order here... to insure that it didn't happen...
As to fuel flow, why do you need to have more fuel...in the engine in turbo engines... you need it because the intake air is heated due to compression from the turbo... and it is a leaner charge in the cyc because of this... fuel as we used to know it provided two things... no three.. cooling of the engine.... lubercation of the heated sections...(lead) and control of the burning in the cyc...(to prevent pre-ignition...knocking) and damage to the internal parts...
When we lean... we reduce the fuel that controls this and to increase the power for the same amount of fuel we cause the fire inside the cyc to get hotter.. and inversely the pressure goes up... to a pulse (explosion) instead of a timed duration... or as we call it a burn. The damage is done when we burn all the fuel... (at peak) and when we are at maximum power.... like cars of old... you could hear them ping... that was the explosion going off inside the cyc... but aircraft engine... are more fragle and work harder.. and thus cant stand to have this pulse... let me put it this way... would you rather have someone push you while you sit in the waggon... or would you rather have someone use a sluge hammer and hit you one time to get you moving......which would do more damage... I'm sure you would choose the push over the slug hammer... but, that is what happens inside your engine as you pull that little red handle back... remember the hammer when you do... but, that is not all that is happening... you also cut back the lubercation and cooling of the exhaust valve and it seat... as well as other things that get more technical such as harmonic vibration.. crank spring.. etc... take my word for it... cruse at 75% or less.. and try to keep the EGT around 75-125... with 125 being perfered... with todays fuels
Another area that I avocate is the cruse climb and decent...if possiable... and after the gear is up and the flaps are up... and all... close the cowel flaps and let the plane go to 125 mph or so... while climbing... it will stay cooler... and make better miles per gallon of gas used...
So to give you a definable answer to your settings... and others... their is no hard and fast number... each plane, engine etc... while made the same... all have their differances... and will all use a little different fuel setting... and will consume at different rated... the varables are pilot tech, engine life, enviroment, fuel, and a host of other things that are happening at the time of the flight...
hope this helps... fly safe... G.M>
gmas replied
We need some more info... like year... turbo or not... etc.... Please expand your question.... any other things that happen to the engine while this is going on... like one or both engines... temp, OP, etc...
Richard Francis added
Plane is a 1976 337G normally aspirated.> MP pressure was stable Fuel flow was stable Normal indications on the engine analyzer RPMs varied from 2500 to 1500 (more or less) Seemed as if both engines were running out of fuel at the same time. Happenned after a climb from sea level to 8000' just as I began to level off. Lasted for about 10sec then returned to normal with no further problems. Fuel contamination? Let me know what you think. Thanks
Richard... I've been there... and believe me it gets interesting... real fast... Ok... here is what I want you to check out first... the fuel tank vents... Have you had the fuel fuller caps changed and complied with the AD... check here ... the filler cap vent... check for bugs plugging... or rubber flapper hardening... also when was the last time you checked the Fuel vent valves...out in the tips... you have to remove the wing tip to access the valve... the shop/parts manual show you that they are able to be disassembled and how to do it... If you are not a A/P mechanic.. You have to have one do it for you...... and they do get plugged... remove, clean and replace... you might want to check to see that all these things are clear and not obstructed..... as well as the vent line that goes to the rear of the tip... look for bugs pluging it up.... common ... disconnect and check for restrictions... to vent air and are causing a vacuum in the fuel system in the tank... as you go up and burn off the fuel... which will cause a fuel starvation problem... Then when you level off and the fuel flow goes down... the tanks can recover... and the engine recovers.
Next I want you or your mechanic to look at the fuel pumps... and check the litle 1/64 inch hole that vents the low pressure diaphram... it is located out at the end of the pump in the casting... next to the adjustment bolt and lock nut... I (my personal airplane) had a problem end up in the club shop where... the fwd engine would quit in flight... hitting the boost pumps would bring it back but.... it led to your anxiety attack... with all kind of things going through my mind... about what was wrong... come to find out it was the witness paint that was put acorss the locking nut to fuel pump body...by one of the young mechanics... and plugged the little vent hole.... which we have found is very important.. not to plug or restrict... now if you don't think that was hard to find... my fuel pressures went all over the place... but mostly the engine would faulter... and exibit the same symptoms your did... Check these things and let me know if one of them are your grimlin.... I think you will find it something simple like what is mentioned above.... If you still have problems ... write.. Good hunting.. G.M> 337 club.
G.M>337Skymasters Club replied
Paul... yes it probably was the gear horn switch on one of the throttle... if you pull the throttle back on each engine with the gear up.... one at a time sometimes you can get the horn to go back off because the switch was just dirty... other times we have seen the wire break off...at the switch also... it should have gone off once you had the gear lowered... if it didn't then you have something else wrong with the dual warning system... hope this helps.. fly safe.. G.M.
Paul Sharp said further
It did go off when I lowered the gear again for landing. So I think it's just one of the switches that has a broken wire or the switch has disintigrated. The wires seemed rather loose on the rear one when I pulled the cowling and looked at them. At least that should be a minor repair; put the last one on myself (front engine) after O/H in November of last year and had it signed off by the mechanics. Thanks for your input.
GMAS>337Skymasters Club replied again
Yep that is probably what it is them... the micro switch that cessna used when they made it is a common one that you can get from a good electronics part store like Newark Electronics.. I don't have the part no.. but you want the one that is computer grade... i.e has gold contact.. inside.. but, in a pinch you can use the regular one... the last time we bought some the were around 1.95 us a piece... The switch body is all the same.. it is the spring and roller length that you have to match... and are not interchangable ... to repair a wire... well I would say that would kinda be a ability thing... where electronic knowledge would be the key factor.. so if you are a ham radio or electronics buff.. I could not see how it would require a A&P to sign it of.. but it is a repair.. and may be one of those grey areas... that the FAA would call... I am sure that if you did it under the watchfull eye of and A&P it would suffice... just don't overtighten those little screws and nuts.. that hold the swich n place... and crack the plastic.. like I do somethimes... they have a torque rating of an ant-arm-lenght.. and just finding them little buggars..sometimes can be frustrating ... I finish it off with a little loc tight.. or gliptol on the threads to keep the nuts from comming loose... (I think they are 6-60 size because they could not make them any smaller just to frustrate us 300 lb gralla sized mechanics) so be careful and not loose them n the engine... hope this helps.. fly safe.. G.M>
gmas replied
Hmmmmm... well that is kinda right... but, leaves a lot to be discussed... First of all when you make a manafold reduction it reduces the power ... less power... less heat... also by reducing the RPM... again makes less power... and actually brings the engines to 75 per cent at sea level... (top of the green) You are right when you say it reduces the amount of fuel... as it does bring the controller back on the lean side... so also does the power drop...leaving it ric h.. It has been my experance with the IO-360 that you can't overheat it by running the power... instead I have found that the cooling air (plennum) pressure is the problem. Most of the baffeling has been cooked so badly and never replaced that it leaks... also the sheet metal baffeling is not the best either... by closing up the holes... even a 1/8 inch one... and sealing around the baffeling... with silicone... replaceing the flexiable baffeling seals... fixing or replacing the cracked and missing metal parts... you will see a big differance in the cooling of the engine. I have seen club members rear engines go from overheating to running cool... just by these changes... Another big bug is the manafold pressure gage... When was the last time it was checked/calbrated.... Also reading its paralax view... becomes a problem... I found some members ran the rear engine harder... thinking the needles are matched... not so... We had the Cont. mfgr rep... come and give a talk on this at one of our meetings.... I will see if I can get him to come to a future meeting again... if enough want to hear about this subject... G.M> 337 Skymasters
Steve then added
Less power less heat. I agree. It would be nice to hear from an engineering standpoint which is more effective in reducing temps, full throttle and full rich or reduced power which as I understand automatically resets the fuel air ratio closer to peak EGT. Try both and check your EGT.
gmas replied again
Having checked the Cont. Eng manual... it appears that The BMP vs. fuel flow in BTU's contrubute to the overall heat of the engine... I found that some other interesting items also appeared when I was doing some calculations... first of all it appears that the engine's RPM has a lot to do with internal heat. I.e. the amout of hp used internally increases when RPM increases... Let me explane... if the engine is turning over 2300 rpm it has a internal hp consumption of around 11 hp.. (746 watts = 1 hp.) But if we increase the RPM to around 2800 it goes to 32 hp. If you multiply the numbers you will see that the heat is increased internally... with no gain... also if the engine uses 0.5 lbs/hp/hr... we can see that the fuel increases just to overcome the internal requirements... increases... Ok... now lets get real technical... The engine was designed to produce max hp... contenious... it was certified such. This is the max Hp/RPM... 28 inches at 2800 rpm.. to produce 210 hp. The amount of heat that is produced to make this HP is taken into consideration and it was cessnas responsibliity to insure amount of air flow... that cont. specified required to provide the necessar cooling... This is what we call plentum pressuere/flow. No matter what MP/RPM you run the engine at... with that amount of air flow the engine will operate within the normal range of temp's. So... what they are saying in the manual... make sure that you have the air flow... and the engine will not over heat... no matter what you run it at... rember it was certified at max power... all day... Now we can't deal with perfect conditions all the time so we baby our engines... and run them at reduced settings and think we are running them cooler... or we run them at full power and a rich condition thinking we are running them cooler... Oh what to do.... well again we go to the engine manual... and guess what... we get the less fuel... less heat... true if we pull them back we lose the full power enrichment... to keep from burning up the engine.... but, Hey... wait a second...you say... look at the EGT... It goes up when we pull back the MP... Yep... it does... but, I ask you does the EGT indicate the heat inside the cyc... or the temp of the escaping gasses... Looking at the Egt... we find this instrument to be only reliative in reading... and will only tell us the temp of the exhaust gasses... run the MP up to full throttle... and grab the mixture control... pull it back... it goes to peak... and then what happens... yep it start going down... but, watch the cyc head temp... it goes up...and up... and up... why? well when the mixture goes past rich...and starts leaning out... the heat of exhaust becomes less but increases in the cyc.. the oxygen becomes geater... (fuel/air mixture) now what burns hotter a oxygen supported flame or a fuel flame... but... you say the EGT decreases... yep it does... because of the time it takes the fuel to burn... it burns hotter (oxygen rich) but, less time... and goes out before the exhaust valve opens.... cooler exhaust... ie the heat is contained within the cyc... and efficency is at maximum... but, it brings us dangeriously close to something else... too... pre ignitions... and we all know what happens then... parts melt... Hmmmmmm... Ok so what is the answer... well if we keep the mix ratio around 11-13:1 we have max power and the engine runs well... but, it produces x units of heat... If on the other hand we reduce the amount of power required... we reduce the fuel required and thus less heat produced... while holding the mixture range. Thus we get x units less heat by doing this... but, if we want even less heat... we can reduce the RPM (to a point) and by reducing the internal power consumption...(see above) .... less heat.... What... you say is all this gibberish... Ok let me put it to you this way... do I generate more heat with the engine running or the engine off...Hmmmm... cant figure it out... well let me know which one you get burned by touching .... engine that not running or one that is running..... thus less fuel (with the mixutre correct... 12:1 or 125 deg on the rich side of peak EGT) manafold pressuer and RPM reduced... or I do with everything at the firewall.... I'll run mine at reduced power... if possiable... I usually try and keep it around 65 per cent power... (RPM/ MP) and guess what at 100 deg rich of peak on the EGT... I get 40 Lbs fuel/ Per Hr..per engine and my engines run in the middle of the green...(18/2300) and still get 160mph... Hmmmmmm great plane huh.. Don't go strictly by EGT... cyc temp and EGt are related but.... seperate... Then again... each of us fly our own way... and have our own way of flying. A good referance is Peter Garason's book "Long Distance Flying" and the Naval Airman's handbook of aeronatics operation. I have seen several good books writen on the subject overseas also. But, the most impressive and factual is the Cont. Engine Overhaul manual. This has the curves to show all the pramaters for operation of the engine.... but, no egt readings. G.M>
gmas then added
And just when you thought it was safe to go out into the air again... I spent the weekend with a great group of mechanics... FAA and Reps... and camped out at the Cont eng reps booth.... I found out some interesting things about the engine... and will make up another letter... if you are interested... But, he did say one thing that I disagree with still but, will pass along anyway... He said that you C A N cool the engine with just the fuel only... of course it would run real rich... and smoke a lot but, that was one of the test that they did during certification... He said that inriching it .... will cool it at any power setting. Now I am confused... I will have to go back to peter Garrison and talk with him again and cite Lorrens' testomoney... Hmmmmmmmm.... G.M>
Jim Rainer replied
I had a Robertson STOL kit on a C-T210 and found the aelirons stiff but responsive. I would not use your autopilot at all with any flaps down - I think it is approved with only normal (not STOL) approach flaps if at all. In the situation you described with updrafts and downdrafts -- you need to have full control yourself. The 337 has light aeliron inputs so I believe it's the STOl kit just as it was on my 210. This is a Robertson characteristic I believe. They are great kits but they degrade the wonderful feel of the 337 w/o them. Also it will drop like a brick if power is lost or cut with full flaps out.
GM @337 Club... replied
You have a small problem .... and no it is not normal ... First make sure your feet are not on the rudders when you swing the gear... by being on the rudders... I mean depressing one of them.... Second... make sure you have the rudder trim set correctly... as this will put pressure on the noise gear too... If the trim is flying correctly... and you have the gear pushing on the rudder pedals... your rudders may be out of specs... and may need to be adjusted...Is your ball on the T&B centered... or are you flying one wing low... and a little x-controlled... While were on this subject... you may want to check the brackets that the pully's are on... espically under the dash back by the firewall... in back of the rudder pedals on the pilot side... check for bracket cracking.. which can be seen by pressing on the rudder pedals and looking for movement at the same time... As to the noise gear... you need to have your mechanic check the gear rollers and track that it runs in... they should be greased at annual time... The shop manual.... shows what to use and where to put it... YOu do have a shop and parts manual for your plane... it is just as important as the POH... we encourage all of our members to have a set... we felt that every plane should have come with a set ... and passed on to the new owner... just like the POH... They are a gold mine of information and one of the better manuals that cessna put out... almost like a military T.O. (tech Order) manuals for the services... it covers everything... The shop manual to work on it... and the parts manual to show you every nut, bolt and screw in the airplane... and the changes in parts through the years... hope this helps... G.M> 337 club.
Blake added
I have the same problem with my skymaster (1975 C337G). The maintenance people couldn't figure it out at the last inspection. I have to crank in right rudder trim after the gear goes up (it can be felt about 3 seconds after the gear motor starts running) and take the trim out after the gear is selected down. At higher speed in the descent more rudder trim is needed. The gear was cycled during maintenance to see if a door was remaining open but that isn't it.
Gerd Wengler added
I had the same problem with my 1976 337G. It cannot be the doors since I had a door removal kit.
Dave Zavoina replied
I ran into a problem like that on a 69 "D" model and assertained that it was in the nose gear steering bungee, that goes from the rudder bar to the nose gear, and after talking to the owner it was decided to ignore this pesky problem due to the expense and it is is a small inconvience that only occurs during the retract cycle.
Jason Friesen said
200 knots
Ian Clapp replied
Thanks, Jason. I would have thought it's a bit higher since the Riley conversions are said to do 225 kt TAS (but perhaps that's at altitude - IAS is probably about 165 kts at 20,000 feet.)
Dave Zavoina replied
The military O-2 Pilots Manual has the proceedure for bailout, however, unless the sucker is on fire or has a structural failure, I'd prefer to ride her in. The rear engine is mounted about 20 inches higher than the front, and I've dropped parachute parcels to boats at sea and haven't had a prop strike yet, but the door wasn't removed either. On a 182 jump plane the door is below the wing, not foreward of it, and with the door removed, it could affect the airflow at the wing root, with disastrous results. Now, getting a jumper to exit with a 210 horsepower cuisinart is another story......
gmas also added
Hi... to answer your question... yes their have been people jump/skydive out of the mixmaster... About 4 years back I had a person write the club and ask how hard it would be to do... No having a 75 with the air stair door.. ment that if anyone opened the door in flight it surely would break off or else damage the inside of the wing where it came up against. But, knowing cessna and the extensive testing that they did.. I figured that they had just about flown the bird in every configuration... including one flap full down and the other retracted.. they said it was an interesting ride but, flew under control... anyway... I fired off a letter to them and asked if the mixmaster cold be flown with the door off.. and surprise.. they said it could but, that I should restrict my speed to under 130 Kt. I passed the infor along and sure enough they said it flew great... a little breezy but fine.. later on I see that the group "Brothers to the Rescue" who also have a web site.. flew on tv with their door off... and were throwing rafts...radio's, food and water out of it... Now as to jumping from the plane... I asked a good friend of mine who is nuts (jumps from perfictly good planes for the movies) .. stunt doubble. What he thought of it... the reply I got was a picture of him jumping from a mixmaster.... He said that with the door off (1978) and the bottom one closed... it was easy to fall out of... he said he turned sideways in the seat and fell out backwards... the speed that they were doing was around 100 kts... On his second jump.. he said that he dove sideways out the door when the pilot made a right turn... at about 45 deg... roll... as he said... nothing to it... we passed his info along.. but, I learned a long time ago in AF training... that they only way I would leave a plane... if it came apart... or was on fire.... and even then I would have my resevations as to if the parachute would work... (smile) If you are woried about the back prop... as he said.. feather it out and your outa their...and home free... Hope this helps...
David Mattix
I'm glad I found this site because I am in th process of purchasing a 337 for business and personal travel but since I am an active skydiver I was entriqued with the thiught of jumping the plane as well. Seems to me the feather the rear prop may be the best bet or a pronounced side slip at jump time. I'd like more info from any sources. Thanks
Frank Buono replied
the speed fairings that I believe you are refering to appear to be the ones produced in Nashville tenn. he advertises in trade a plane in the 337 cessna section. he list boom fairings ,wing tips and other items which to me look rather ugly but if they perform as well as reported they may be well worth the price and ugliness. good luck Frank
Michael Hayes replied
On page 3-8 of the Cessena 337 owners manual there is a chart for zerro thrust Propeller RPM With the front engine at 2800 RPM and at 2500' rear engine is now set at 2320 RPM, at 5000' set at 2410 RPM, at 7500' set RPM at 2510 With the rear engine at 2800 RPM and at 2500' front egine is now set at 1930 RPM, at 5000' set at 2010 RPM, at 7500" set at 2090 RPM
Simualate single - engine procedures can also be practiced by setting the propeller RPM of an idling engine at zero thrust as shown in this Figure.
Remember an unfeather propeller causes a lot of drag.
Good luck, Michael Hayes
Rufus Crowe replied
We have a 1967 337B and the owners manual has no such chart on page 3-8. There is no mention, whatsoever, in the manual about simulated single engine out power settings....??
Appreciate the information, Thanks Again!
Michael Hayes then pointed out
The information I sent you is out on my manual for a 1970 model E- 337. The airplanes are for the most part unchanged that information should work in your model.