Quiet flying...too quiet...

9 posts in this topic

Posted

Thought I would share an experience with all of you.  This 4th of July I went flying with a buddy up in the mountains.  He has a 108-3 Super Stinson.  It has a Continental O-470 and performs really well.  We got an early start and flew to our mountain destination without issues.  We had another buddy meet us in his Cessna 182.  We ate breakfast and then started home.  We climbed up to 11,000' MSL to get over a mountain ridge.  This was my first time to fly with my friend and I showed him how to fly different formation positions off of the 182.  The 182 was quite a bit faster than us, so we asked the 182 to give us one.  I showed him how to use the energy with climbing and descending to keep up with a faster straight and level aircraft.  This whole time we were holding about 2600 RPM and had the prop fixed at full climb pitch for ease.  The 182 began descending as we got within about 25nm to our airport.  We decided to break up to enter the airport's airspace, so the 182 went straight ahead as me and my buddy did a 360 for spacing which was right over a big reservoir at about 1500' AGL.  As soon as we made a complete 360 I saw the RPM burble and then rapidly fall!  My buddy took the aircraft back from me, I looked out the window and told him we had the state park with a lot of dirt roads beneath us.  He tried everything to get a restart, but it didn't fire at all!  What surprised both of us was our sink rate!  We had practiced engine outs before, but this was the first time we had experienced the drag of a prop that isn't even idling...it was a lot of drag!  Anyway, we immediately prepared to land, but being the 4th of July, there were people and cars on every dirt road!  I saw one dirt road that was completely open and we decided to go for it.  At this point we had a few hundred feet to lose to get her on the road.  My buddy did a great job slipping to lose altitude, we suddenly realized our dirt road was actually a concrete path that was too narrow and curvy to land on so we shifted off of it to the field next to it full of cactus and prairie dog colonies.  He got it down in the field and after a few bumps we came to a stop.  We got out and after emptying our shorts, we began to troubleshoot things.  I asked if he had done anything different or done any maintenance recently.  And guess what...he had just added the Mogas STC and we were flying with Mogas for the first time.  It all made sense now.  We had no problems on the way into the mountain with a nice cool morning, but flying back we had the engine fire walled and we're working it hard with the formation stuff, while descending into 100 degree temps...Vapor Lock!!!

His Stinson is all gravity fuel feed, no mechanical or electrical fuel pump, so there is no way to force feed the fuel through a vapor lock, thus no restart for us.

I'm telling you guys this because most of our little planes are burning Mogas.  So, it would be a great idea to look at the dangers of running Mogas.  It is not regulated like avgas, so you can get different values of Mogas that can be more susceptible to vapor lock.  Mogas is more likely to vapor lock at high altitudes.  Mogas should be as fresh as possible, do not let it sit in your wing tanks for months.

This shouldn't be taken as Mogas is bad, this info should be used as a warning.  If you want to be prepared for vapor lock possibilities, install a small electric fuel pump (A small facet works great and is cheap), wrapping you exhaust reduces heat under the cowl, maximize airflow through your cowl with proper baffling, wrap your fuel lines with fire sleeve, route your fuel lines away from exhaust pipes, if you can't avoid proximity to pipes look at using a shroud.  Look at shroud materials...don't use aluminum, it acts as a heat sync!

Things I learned as a Pilot playing passenger...when you ride in a new plane, take the time to learn the location of all controls/switches so that you can help out in an emergency and not just be a sandbag in the right seat!  Sure the PIC is ultimately responsible, but a passenger with thousands of hours that doesn't know the cockpit layout holds the value of an empty seat!  The Fuel Master on a Stinson is on the Dash and has a Left/Right/Off position...no "Both"

Anyway, just think about it so you don't experience the deafening silence of your engine vapor locking!

By the way, no human injuries, but we probably murdered some prairie dogs :)

 

See ya,

Ron

 

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Posted

Wow, quite the ride, glad it ended well.  I use mogas all the time, never get very high though.  Gave me some things to think about.  I've seen a stopped prop several times, and it does get your attention, no doubt.  Can't say that the Avid drops like a rock, although I was concerned with maintaining airspeed and put the nose down as much as I needed to, to keep about 60 MPH.   Jim Chuk

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Posted

Great article, thanks! Three thoughts:

1) the fuel system wasn't designed for mogas, and the original Stinson temperature tests might have allowed line temps that mogas doesn't handle. The STC process is many times a pop-corn test that has little rigor, unlike the original certification testing (I am an engineer for an OEM, and have seen horror stories in STCs) so it didn't fully explore the corner you backed into. I bet a little line wrapping or separation would cure it, now that real test data is at hand (the hard way).

2) There is nothing quite so helpful as a fuel boost pump to stretch your glide! I have one on the shelf in my hangar, doing no good. Based on your story, I am installing it this weekend!

3) You guys make a good team, be proud.

 

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Posted

Thanks for the heads up!  One thing too with mogas, make sure your tanks are well vented, it does help.  Glad it turned out well!  I know this feeling all too well! 

When she quit did you let the prop windmill or did you pull the nose up to slow down enough to get the prop to stop?  I can tell you this flying side x side with another cub, the one that stopped the prop had a vastly lower sink rate than the one with the prop windmilling.  That prop becomes a huge speed brake if you let it windmill.  I know this is not in the POH but its a really good thing to do if your at the point that you are not going to make a restart, you ran out of gas, there is oil all over the windscreen and a piston and rod sticking out of the cowling etc.

:BC:

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Posted

We didn't even think about doing that...Makes sense though!

That is why I love this forum...a lot of experience!

Thanks,

Ron

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Posted (edited)

Hi Ron, another item checked off your 'Bucket List' eh? Glad it worked out and thanks for sharing.

[edit] Leni thanks for the tip!

Edited by dholly
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Posted

Ron:

 

You made a very good point of the fact that practicing engine out with the engine idling is much different than actually having the engine stopped completely. That can be seen by idling your aircraft with the brakes off. There is some thrust and the aircraft will move, But when the engine is dead the prop is just drag.

Knowing this, my group of back country flyers decided to go out to one of our high desert dry lakes and set up an Accuracy Dead Stick practice.

We selected Lake El Mirage just south of Edwards AFB where the ultimate dead sticks were done with the early shuttle.

We set up a couple of traffic cones at the desired touch down target line and then place 100 foot markers before and after that spot so we can tell pilots haw far off they were.

We found that after 3-5 tries we would improve from being as high as 300 yards off to actually touching within 50 feet of the target line.

Depending on the aircraft, engine compression and prop size and pitch, some props would stop (Rotax and Jabiru) and others, such as the Maule would keep turning and give even more drag.

With 3x 5 miles of smooth landing surface we can also practice the "Deadly Turn Back" where we determine our minimal turn back AGL combined with our skills.

We also test different take off configurations to find the best combination for the shortest take off.

We invite anyone in the Southern California area to join us at our monthly practice sessions.

I have written about this practice in AOPA and EAA Sport Pilot and have presented Wings Seminars on the subject.

We practice once per month, weather permitting.

Interested pilots can contact me at skypics234@aol.com.

Better to have skills you done need than to need skills you don't have.

John

 

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Posted

Ron:

 

You made a very good point of the fact that practicing engine out with the engine idling is much different than actually having the engine stopped completely. That can be seen by idling your aircraft with the brakes off. There is some thrust and the aircraft will move, But when the engine is dead the prop is just drag.

Knowing this, my group of back country flyers decided to go out to one of our high desert dry lakes and set up an Accuracy Dead Stick practice.

We selected Lake El Mirage just south of Edwards AFB where the ultimate dead sticks were done with the early shuttle.

We set up a couple of traffic cones at the desired touch down target line and then place 100 foot markers before and after that spot so we can tell pilots haw far off they were.

We found that after 3-5 tries we would improve from being as high as 300 yards off to actually touching within 50 feet of the target line.

Depending on the aircraft, engine compression and prop size and pitch, some props would stop (Rotax and Jabiru) and others, such as the Maule would keep turning and give even more drag.

With 3x 5 miles of smooth landing surface we can also practice the "Deadly Turn Back" where we determine our minimal turn back AGL combined with our skills.

We also test different take off configurations to find the best combination for the shortest take off.

We invite anyone in the Southern California area to join us at our monthly practice sessions.

I have written about this practice in AOPA and EAA Sport Pilot and have presented Wings Seminars on the subject.

We practice once per month, weather permitting.

Interested pilots can contact me at skypics234@aol.com.

Better to have skills you done need than to need skills you don't have.

John

 

Wish I  lived near you... this is just the thing I like to practice!

Please consider posting a new topic explaining how you set up the deadstick practice, what you brief newbies (do's and dont's), and tips for getting good doing this.  Or maybe a link to one of your articles.

Thanks!

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Posted

John,

Thanks for the info and training ideas.  I too would like to hear more on your results and lessons learned.

 

Thanks,

Ron

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