I had a terrible scare a couple of weeks ago. After a short flight to my cottage strip I ran a few errands and got back into the Maule after about a half hour on the ground. On climbout at about 100 feet the engine died (over water). A couple seconds later she caught again and revved right up to full power, then died again . Seconds later same thing, this time it stayed running. The only thing I had time to do was scan the panel, and switch tanks. I got home without incident but was afraid to tell anyone the story because I thought it was my fault with tank selection on takeoff. I did indeed take off with the left tank selected not both as recommended in the POH. There was fuel in the left tank however so there was no reason the engine should have faltered. Another time this happened to me on downwind when I switched tanks from left to both but the engine just sputtered once, still enough to make my heart skip. It wasn't until last weekend I told the story to some other Maule pilots at a fly-in. One of them said I likely had a vapour lock and that he has seen this happen before on Lycoming engines and that you should always take off, land and switch tanks with the fuel boost pump on. If this is true, should this not be in the Maule POH? My engine is the IO540. Has anyone ever had a similar occurrence?
Check out my private strip on Google Earth at 45.49.57 N 76.45.44 W. Annual fly-in last week of July. Wheels & floats welcome.
First of all it's not going to vapor lock from firewall aft, and you do have an engine driven fuel pump supplying fuel at a specific pressure to Fuel Inj Sys. If EDP is good of course there is no need for electric boost pump as you will be supplying too much fuel and volume in relation to what the engine needs. Most high wing aircraft do not require boost pump on departure, for example, the cessna 185 and when elect pump required from EDP failure, you use low pressure side only, otherwise mixture runs very rich. Low wing pipers are another story... Water in gas, Fuel selector in detent, one wing low in turn? You might also have an engine driven pump on verge of failure? What is your fuel flow (pressure gauge) indicating during anomally as this could help a great deal with troubleshooting system? Good luck troubleshooting, but I'd look somewhere else for problem as turning on boost pump may make it run, but there's probably another issue causing problem. Also departure with BOTH tanks selected is not a recommendation, but is a required factory procedure that is there for a purpose, to prevent fuel starvation.
It is common for mud daubers to enter the tank vent lines and block them.
Try blowing back through them using a tube that covers the anti siphon hole. This is if you have the earlier individual tank vent system.
Often, fuel caps have been replaced with non working or no vents.
If air cannot get into the tanks, fuel cannot get out especially fast enough for 23 gph from one tank on takeoff power.
Was the fuel selector fully in the detent.
If only one tank is selected and the aircraft is slightly yawed on takeoff along with the strong P factor, the tank outlets can unport thus the change to fuel valves that incorporate LEFT, RIGHT, OFF and BOTH.
Hope it does'nt happen again.
In my M4 with Continental IO360D if you left the fuel pump on with engine at idle it would run very rich and just about stall out. I tried this with the Lycoming IO540 and no difference at idle or full power and no change in fuel flow with electric boost pump on or off. Regardless, I will start looking into the tank venting system as this seems logical. The aircraft is a 2005 year model so would it have the individual tank vent system? And if so, does that mean the caps would be non-venting type?
Check out my private strip on Google Earth at 45.49.57 N 76.45.44 W. Annual fly-in last week of July. Wheels & floats welcome.
In a 2005 you will have the later combined venting system which is not as prone to mud dauber blockage,. So lack of air venting was probably not the cuprit. Blow into the vent underwing near strut attach to be sure.
You should have four vented caps.
As you were on one tank which may have been relatively low my guess is a slip or yaw (uncoordination) unported the lines. Ie Fuel was sloshed outboard away frm the fuel line outlets of the tank.
For takeoff or landing when tanks are down (not full) or you are not certain of quantity use BOTH position.
There is a lot of very good information in the Maule POH and in the Lyc Operating Handbook.
As Jeremy mentioned, even with say LH Main Half Full, it doesn't take that much of a LH wing down, be it a slightly uncoordinated turn, or a yaw, it's very easy to unport the fuel pickups. With Both Tanks selected that fuel in other wing gathers deeper over pickups preventing fuel starvation. Any time I'm near the ground and maneuvering at all, I select both including T/O's and Landings?
The fuel selector on BOTH for T/O and landing sounds very logical considering that in a shallow left turnout, the fuel could easily unport from the left tank if you had too much right rudder. I'm surprised this never happened to me all the years I flew my M4 with only LEFT and RIGHT options.
How do most guys manage the fuel quantities when the tanks can crossfeed level when parked or flying with selector on BOTH? I like to know that if I fill the RIGHT tank before takeoff, then fly .75 hours at 16 GPH I used approx 12 gallons. Theoretically, I have a good idea how much fuel is left in that tank. Now I land on BOTH and forget to select RIGHT, I come back next week to fly and I've got no idea my quantity anymore because the tanks have self-levelled.
I find it easier to fill and use from one smaller tank because I fly alot of short trips into a short strip with heavy loads and want to keep the gross weight down and I don't want to fill both tanks all the time. What do you guys do, rely on the gauges??
Check out my private strip on Google Earth at 45.49.57 N 76.45.44 W. Annual fly-in last week of July. Wheels & floats welcome.
you said in your post that the engine just died? did it sputter any before it died? and when you said it caugh, where you trying to start it or what? i guess am asking did the the engine just go cold turkey off with no warning.....thanks
I burn between 10 to 12 gallons on most of my local flights with tourists. I leave tanks on 'both' most of time so fuel is pretty much level across both tanks. I fill LH main with 12 gallons, which means I've got 21 gallon in LH side and 9 gallons in RH side until the fuel level evens out between sides. If in doubt I dipstick both tanks before fueling to see where I'm at. This works for me and my purposes, but depending upon load, etc, there are times where I do have to vary quantities, I just dip tanks to verify?
I concur with Jim. Dipsticking both tanks before flight tells you exactly what you have regardless of how uneven the ground you parked on is.
Don't trust the gauges atall.
Never fill the tanks with BOTH or OFF selected as the fuel will transfeed as you fill.
If full tanks are left for a period on uneven ground and BOTH or OFF are selected, you may lose many gallons out of the vents by next flight. Even a lunch break. so dip tanks before flight.
The statistics I read state that nearly 75% of the pilot error accident/incidents are running out of fuel.
How stupid can pilots be??
I believe that the ancient FAA rule requiring 30 mins reserve is part of the problem. Modern aircraft have greater tanks thus more time to run over rich, or buck a headwind etc, so that 30 mins can be used up before you reach the normal fuel consumption time.
If I land with less than an hour of fuel I would consider that to be a failure in fuel planning. For me that's 1/4 tank in the mains, plus I always have about 4 gallons in the aux tanks.
I am an AME in Richland, Washington. Please call for an appointment!
CS49 asked about the engine failure. To answer your question- yes the engine died with no sputter whatsoever (just like complete fuel starvation) then before the prop stopped windmilling it came back to life on its own. This happened twice about 5 seconds apart. I was in a slight left wing down attitude with left tank selected. What I've learned from everyone has me convinced that the left tank fuel level was low enough to unport from the tank feed lines and allowed a gulp of air into the system. I was lucky to not lose the aircraft. It was stupid and I'll always use BOTH from now on and manage the fuel better. Is there more than one tank feed line on each tank? I asssume it's on the inboard side only? There's another post now about wooden dipsticks so I'll make one and calibrate it for the tundra tires.
Check out my private strip on Google Earth at 45.49.57 N 76.45.44 W. Annual fly-in last week of July. Wheels & floats welcome.
There are two fuel lines from inboard side of each main tank.
One at front goes down front door post and one at rear goes down rear door post.
I strongly encourage all pilots to attend an annual inspection to fully learn and understand all the systems, even though you may have to compensate the mechanic for extra time.
Studying the parts manual and the Engine operators handbook will also reveal masses of interesting information and help all to become safer.
According to the Lycoming Key Operations Manual, this is what they have to say about using the boost pump:
"An effective continuous fuel supply is provided by use of the fuel boost pump. As a general recommendation, the fuel boost pump should be used with Lycoming engines in all conditions where there is any possibility of excessive vapor formation, or when a temporary cessation of fuel flow would introduce undesirable hazards. The conditions under which Lycoming recommends operation of the fuel boost pump are as follows:
1. Every takeoff.
2. Climb after takeoff unless Pilot’s Operating Handbook says it is not necessary.
3. When switching fuel selectors from one separate fuel tank to another, the fuel boost pump should be “on” in the new tank until the operator is assured there will be no interruption of the fuel flow.
4. Every landing approach.
5. Any time the fuel pressure is fluctuating, and the engine is affected by the fluctuation.
6. Hot weather, hot engine ground operation where fuel vapor problems cause erratic engine operation.
7. Some General Aviation aircraft require the use of the fuel boost pump during high-altitude flight. This will be spelled out in the Pilot’s Operating Handbook.
8. If the engine-mounted fuel pump fails.
If the fuel boost pump is used during ground operation, don’t fail to check the condition of the engine-mounted fuel pump before takeoff by turning the boost pump off briefly, and then back “on” for takeoff. If the engine-mounted pump has failed, it would be safer to know that on the ground rather than in the air when the fuel boost pump is turned “off.”
When in doubt, do the safest thing and use the fuel boost pump with Lycoming engines. Don’t be “stingy” with the boost pump. In most cases, they last the overhaul life of the engine, and are then exchanged or overhauled themselves. AS A REMINDER, the airframe Pilot’s Operating Handbook is the authority if boost pump information is spelled out in it.
Since the Maule POH really doesn't address this, shouldn't we follow the Lycoming manual?
Check out my private strip on Google Earth at 45.49.57 N 76.45.44 W. Annual fly-in last week of July. Wheels & floats welcome.
(over water). A couple seconds later she caught again and revved right up to full power, then died again 
