Results 1 to 17 of 17

Thread: A Gremlin that didn't kill me . . .

  1. #1
    Member Sierra Hotel's Avatar
    Join Date
    Feb 2007
    Location
    Chugiak
    Posts
    637

    Default A Gremlin that didn't kill me . . .

    OK sportsfans, I flew up to Talkeetna a couple of Saturdays ago - just because. Beautiful morning, hoping to get there and back before forecast winds kicked up. I landed, used the facilities, and talked to the briefer. AWOS back at Birchwood was calling for calm winds. hopped back into the plane, took off, and at about 400 agl got a "hiccup" in the normally smooth running PPonk engine. I pulled carb heat on immediately, dropped the nose a bit to build some airspeed. The engine smooted right out so I and continued on. I flew the rest of the way home with partial carb heat, monitoring the carb heat temp (stayed in the 80's all the way home), and the engine ran just fine.

    Upon arriving at PABV, the winds were blowing 20 and gusting to 35, 20-40 degrees off the runway, so I had to work to get her down on the long and wide runway. Once down, I taxi clear of the runway and head to my tiedown. Right in the middle of the taxiway the engine quits. No hiccup, no burble, just dies. I check my fuel selector (Both), and tried a restart. It turns over fine, but doesn't start. I go to prime a couple of times, and there's literally no pressure on the primer, leaving me to believe I'm out of fuel

    However, I took off with 45 gallons from Birchwood, and used less than 20 on the round trip (I do have a totalizer). A couple of guys passing by on the ramp helped me to push her back to the tie down, and I got it secured in the relatively high winds (I came back the next day to put the wing covers on - not possible in the wind that day). I dipped both tanks, and found that my R tank had the 25 gallons I thought to have in my tanks, but the L tank was bone dry. This is the point at which I REALLY wanted a drink! If this had happened just five minutes earlier during that nasty approach in that wind . . .

    So I get with my mechanic and he checked out the plane. Parked it in a hangar and checked the vent system. It checked OK, but the vent was badly out of position, which accounts for the uneven fuel flow. There's no way of knowing if the vent line was blocked and an obstruction was blown out - but it's venting properly now . . .

    The fuel valve checked out OK, so it was time for a functional check. I taxied out and did a run up on both tanks, and then ran on each tank separately for about 5 minutes at run-up rpms (1700). Everything checked out fine, so I taxied onto the runway and took off.

    I climbed up to 5,000 ft. and flew in a circle for an hour, staying within easy glide distance of the airport, I flew on Both, L, and R about equal time to check out operation.

    Everything worked as advertised. I flew five TnG's, and landed to refuel. The fuel flow meter showed 18.3 gallons used in the 1.2 hrs., and I refueled exactly 18.3 gallons, filling to the filler necks, 9.3 in the R and 9.0 in the L.

    At this point my mechanic and I have decided that it was one of those "gremlins" . . . most likely associated with a vent problem, but I'll never know for sure.

    I also learned a lot about the fuel system in my airplane. While familiar with it, I think I know it now, and understand how important the positioning of that little fuel vent is. The Cessna service manual gives a .09" tolerance for placement - that's right - nine 1/100th's of an inch.

    SH



  2. #2
    Member Float Pilot's Avatar
    Join Date
    Oct 2006
    Location
    Kachemak Bay Alaska
    Posts
    4,218

    Default

    WOW...... I wonder what the heck was in there ??? Was that a C-180 ??
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

  3. #3
    Member Sierra Hotel's Avatar
    Join Date
    Feb 2007
    Location
    Chugiak
    Posts
    637

    Default

    FP, it's a '58 182 with a PPonk O-520. Standard fuel tanks (65 gallons, 55 useable).

  4. #4
    Member 4merguide's Avatar
    Join Date
    Feb 2012
    Location
    Kenai Peninsula, Alaska
    Posts
    9,749

    Default

    Quote Originally Posted by Sierra Hotel View Post
    OK sportsfans, I flew up to Talkeetna a couple of Saturdays ago - just because. Beautiful morning, hoping to get there and back before forecast winds kicked up. I landed, used the facilities, and talked to the briefer. AWOS back at Birchwood was calling for calm winds. hopped back into the plane, took off, and at about 400 agl got a "hiccup" in the normally smooth running PPonk engine. I pulled carb heat on immediately, dropped the nose a bit to build some airspeed. The engine smooted right out so I and continued on. I flew the rest of the way home with partial carb heat, monitoring the carb heat temp (stayed in the 80's all the way home), and the engine ran just fine.

    Upon arriving at PABV, the winds were blowing 20 and gusting to 35, 20-40 degrees off the runway, so I had to work to get her down on the long and wide runway. Once down, I taxi clear of the runway and head to my tiedown. Right in the middle of the taxiway the engine quits. No hiccup, no burble, just dies. I check my fuel selector (Both), and tried a restart. It turns over fine, but doesn't start. I go to prime a couple of times, and there's literally no pressure on the primer, leaving me to believe I'm out of fuel

    However, I took off with 45 gallons from Birchwood, and used less than 20 on the round trip (I do have a totalizer). A couple of guys passing by on the ramp helped me to push her back to the tie down, and I got it secured in the relatively high winds (I came back the next day to put the wing covers on - not possible in the wind that day). I dipped both tanks, and found that my R tank had the 25 gallons I thought to have in my tanks, but the L tank was bone dry. This is the point at which I REALLY wanted a drink! If this had happened just five minutes earlier during that nasty approach in that wind . . .

    So I get with my mechanic and he checked out the plane. Parked it in a hangar and checked the vent system. It checked OK, but the vent was badly out of position, which accounts for the uneven fuel flow. There's no way of knowing if the vent line was blocked and an obstruction was blown out - but it's venting properly now . . .

    The fuel valve checked out OK, so it was time for a functional check. I taxied out and did a run up on both tanks, and then ran on each tank separately for about 5 minutes at run-up rpms (1700). Everything checked out fine, so I taxied onto the runway and took off.

    I climbed up to 5,000 ft. and flew in a circle for an hour, staying within easy glide distance of the airport, I flew on Both, L, and R about equal time to check out operation.

    Everything worked as advertised. I flew five TnG's, and landed to refuel. The fuel flow meter showed 18.3 gallons used in the 1.2 hrs., and I refueled exactly 18.3 gallons, filling to the filler necks, 9.3 in the R and 9.0 in the L.

    At this point my mechanic and I have decided that it was one of those "gremlins" . . . most likely associated with a vent problem, but I'll never know for sure.

    I also learned a lot about the fuel system in my airplane. While familiar with it, I think I know it now, and understand how important the positioning of that little fuel vent is. The Cessna service manual gives a .09" tolerance for placement - that's right - nine 1/100th's of an inch.

    SH



    Well I'm glad the gremlin decided to give you the extra 5 minutes.....
    Sheep hunting...... the pain goes away, but the stupidity remains...!!!

  5. #5

    Default

    Wow, glad that worked out as it did.
    14 Days to Alaska
    Also available on Kindle and Nook

  6. #6
    Member Sierra Hotel's Avatar
    Join Date
    Feb 2007
    Location
    Chugiak
    Posts
    637

    Default

    That makes a few of us that've glad the plane gave me five more minutes . . . .

  7. #7
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Late fall conditions were ususually perfect for making condensation. It hasn't been much better lately with the temps bobbing above and below freezing. It's hard to get ice through those sumps. My plane went into a hanger for maintenance a few days ago. The amount of water that came out of my right tank was alarming. My fillers don't leak. My plane parks right wing low and gets some fuel transfer every time I park. Guess where the water goes and what it turns into when the temps drop? I sump aggressively every chance I get when the wings warm enough to melt ice.

    Didn't you notice your fuel gauges during your flight?

  8. #8
    Member
    Join Date
    Jun 2011
    Location
    Tennessee
    Posts
    1,462

    Default

    Quote Originally Posted by Mr. Pid View Post
    Late fall conditions were ususually perfect for making condensation. It hasn't been much better lately with the temps bobbing above and below freezing. It's hard to get ice through those sumps. My plane went into a hanger for maintenance a few days ago. The amount of water that came out of my right tank was alarming. My fillers don't leak. My plane parks right wing low and gets some fuel transfer every time I park. Guess where the water goes and what it turns into when the temps drop? I sump aggressively every chance I get when the wings warm enough to melt ice.

    Didn't you notice your fuel gauges during your flight?
    Mr. Pid, you know to not depend upon the fuel gauges. From my comfortable armchair, I'd have to agree with the vent issue.

    Congrats on your aggressive sump draining. It's the right thing to do . . . . .

  9. #9
    Member Sierra Hotel's Avatar
    Join Date
    Feb 2007
    Location
    Chugiak
    Posts
    637

    Default

    Mr. Pid, the winds at 1500-4500' were bouncing me around pretty good, and to be truthful I wasn't watching the notoriously inaccurate Cessna fuel gauges hardly at all. We thought of ice also, and maybe putting it in the hangar for those couple of hours thawed it out, leaving nothing to find. If I can get it into a hangar for a day or so in the near future I'll sump it well and see if I get any water.

  10. #10
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Don't get too caught up in the "inaccurate" rhetoric. Tools are tools. I never had any problem making my needles bounce by flying wing low/wing high. That's pretty good indication that I'm not empty. On one occasion I had quarter tanks and the R gauge read full. That was because I failed to replace the fuel cap and all my fuel was being siphoned out. Those gauges work pretty well in my experience.

    When in doubt, isopropyl alcohol works pretty well on tank ice.

  11. #11
    Member
    Join Date
    Jun 2011
    Location
    Tennessee
    Posts
    1,462

    Default

    Quote Originally Posted by Mr. Pid View Post
    Don't get too caught up in the "inaccurate" rhetoric. Tools are tools. I never had any problem making my needles bounce by flying wing low/wing high. That's pretty good indication that I'm not empty. On one occasion I had quarter tanks and the R gauge read full. That was because I failed to replace the fuel cap and all my fuel was being siphoned out. Those gauges work pretty well in my experience.

    When in doubt, isopropyl alcohol works pretty well on tank ice.
    You're right about the isopropyl alcohol (not to be confused with rubbing alcohol.) Back in the day, we used one-ounce in each tank for DC-3s, DC-4s and DC-6s, as well as for the Connies. I used 1/2-ounce in each tank for the Super Cubs, C-180s, and C-206s.

  12. #12

    Default

    The present Lycoming standard for fuel in many of the lower power engines that they implemented a couple of years ago, allows for as much as a 1% methanol concentration in the fuel. That is .5 gallon in my 50 gal Cessna. Way more than is needed to absorb most water in the fuel issues. The problem is making sure that the alcohol gets mixed up enough to do its thing. Twenty years before I bought my plane, it had a forced landing due to ice in the fuel line (in S. Dakota). Not a good thing.

  13. #13
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    Methanol? I'm unfamiliar with methanol additives. I buy isopropyl by the case. I don't like adding it to Cessna bladders but will if I suspect ice is present.

    From TCM's SIL99-2
    ADDITIVES
    Under certain ambient conditions of temperature/humidity, water can be supported in the fuel in sufficient quantities to create restrictive ice formation along various segments of fuel system. To alleviate the possibility of this occurring, it is permissible to add Isopropyl Alcohol to the fuel supply in quantities not to exceed 3 percent of the total. Also, Diethylene Glycol Monomethyl Ether (DEGMME) conforming to military specification MIL-DTL-85470B, if approved for use in the aircraft fuel system by the aircraft manufacturer, may be added for this purpose. The DEGMME compound must be carefully mixed with the fuel in concentrations not to exceed 0.15 percent by volume.

    SIL99-2

    
    And this from Lycoming SI 1070Q
    NOTE
    Isopropyl alcohol in amounts not to exceed 1% by volume may be added to the aviation fuel (not automotive fuel) to prevent ice formation in fuel lines and tanks. Although approved for use in Lycoming engines, do not use isopropyl alcohol in the aircraft fuel systems unless recommended by the aircraft manufacturer.

  14. #14
    Member
    Join Date
    Jun 2011
    Location
    Tennessee
    Posts
    1,462

    Default

    Quote Originally Posted by cessna308 View Post
    The present Lycoming standard for fuel in many of the lower power engines that they implemented a couple of years ago, allows for as much as a 1% methanol concentration in the fuel. That is .5 gallon in my 50 gal Cessna. Way more than is needed to absorb most water in the fuel issues. The problem is making sure that the alcohol gets mixed up enough to do its thing. Twenty years before I bought my plane, it had a forced landing due to ice in the fuel line (in S. Dakota). Not a good thing.


    Okay - - - - - what's a "lower power" engine ???

  15. #15

    Default

    Meant to type ethanol. Ethanol free automotive gas is available in many local areas. As for lower power engines, they have a list of the engines that are approved for the new fuel standard where isopropyl alcohol is allowed. I didn't see any 6 cyl engines listed in table B2 of the Lycoming standard, only O and IO 360 engines, although some older 435 and 490 cu in engines were already on the list. As the Lyc info says, getting automotive gas that meets its standards is hard to prove. Avgas is required to meet certain standards. Auto gas might be anything. I only posted the comment to state how much alcohol is allowed. I would use it too if I was afraid of ice. My plane has a wet wing, and I don't know if alcohol causes a problem with the sealant, and hope I don't need to find out. I put the Monarch fuel caps on it years ago. Condensation is the only issue now. But as you say, ice in the fuel line is very serious.

    Read the bulletin here
    http://www.lycoming.textron.com/supp...fs/SI1070Q.pdf

  16. #16
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    The Lycoming SI allows the addition of isopropyl deicer in aircraft fuel only and specifically disqualifies mogas. I've never seen any aircraft engine or airframe approval of anything that contains ethanol.

  17. #17
    Member
    Join Date
    Jun 2011
    Location
    Tennessee
    Posts
    1,462

    Default

    Mr. Pid is right once again. Besides, isn't the ice (read water, which later freezes) formed in the tanks rather than in the fuel lines which are always filled to capacity with fuel? Seems that the water (and ice) are formed upstream of the filled fuel lines . . . . .

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •