Multiengine question

[Henning]

Me stoooopid.

So, it's education time, as I need to learn this. How does the fuel injection system work? I have only a basic knowledge.

What I'm especially interested in... What are the failure modes that could cause a dual engine failure on a Seneca. So far, I can think of...

1. Pilot error in its many forms (both on crossfeed, crossfeed in the wrong direction after engine failure, pulling the mixtures, incorrectly identifying and shutting down the wrong engine, etc. etc.)
2. Fuel contamination.
3. ??? (I'm not in much of a thinking mode yet today, got home at 3:30 AM)

Water in the fuel and cold weather spells for potential ice accumulation in the fuel servo, and this can effect and shut down both engines. The fuel servos put simply regulate the amount of fuel that goes to the distribution block and consequently the nozzles. Mechanical fuel injection as it is used on aircraft, is a constant flow excess volume system feeding the servo. The positive pressure in the feed system is maintained by the "pill", a restricting orifice in the fuel return port which is post fuel usage port. If you clog the pill, the pressure at the fuel usage port increases which in turn increases the pressure and flow at the nozzles which will in effect richen the mixture. The ice can further accumulate and totally block the fuel flow to the usage port. If that happenned to me, especially if I had just fuel the aircraft, I would suspect moisture in the fuel and ice blocking the pill. The reason I would suspect this, is because until PROVEN otherwise, I always suspect what will kill me. Wishfull thinking has no place in aviation.

 

[poadeleted20]

The question assumes facts not in evidence, specifically, that I would continue the flight after the engine recovers. That just ain't happening.

 

[Ed Guthrie]

I'm late to the party, but here's my answer: What Henning wrote (all).

Well, I have one minor difference: Hazard pay starts at less that 1" split.

Furthermore, I would have an immediate ground session with the CFI involved. If s/he did not readily admit to a serious lapse in judgment I wouldn't be flying with him/her again, and, furthermore, in that case no way, no how would s/he ever give me flight instruction again. The flight instructor blew it--big time--the classic smoking crater looking for a location.

 

[bbchien]

The question assumes facts not in evidence, specifically, that I would continue the flight after the engine recovers. That just ain't happening.

Mag gear? I'm not so sure. After all I had it happen...it smoothed out just fine, then about fifteen mnutes later it went to super-rough all by itself....

The point being, you can't really tell in the air. OK for local flight, but crossing the pond,

"chicken man.......he's everywhere, he's everywhere...."

 

[gismo]

Turbo and oxygen, I assume? What's the glide ratio on the Bo? Where did you cross?

Oxygen (usually) but no turbo. There are two narrow crossings, one approximately between Menominee MI (southernmost point in the UP) and just north of Traverse City is less than 39 nm from shore (Door County) to shore (Manitou Islands). The other is between Manitowoc WI and Ludington MI and that's a bit under 44 nm. The Bonanza glides at about 1.8 nm per 1000 ft altitude which means you'd lose 11,000 from the middle of the northern route or a bit more than 12000 from the middle of the southern crossing. On the north route (which is what I flew most often) I'd climb to at least 12000 MSL and usually 13000. On the south route it was 13000-14000. The biggest downside was when going west I'd be starting from an airport fairly near the shore and it seemed like there was always a pretty stiff westerly wind that combined with the necessary best ROC speed would reduce my groundspeed (should that be waterspeed?) to something in the double digit range.

Where I cross to go to CAD, ideal conditions and assuming a 9:1 glide, 15,500 feet is the absolute minimum to glide near shore... And I have no oxygen.

Nope. It doesn't have oxygen built-in, and I'm not going to buy an oxygen system for a flight or two a year in a rental plane.

With the gear retracted and props feathered, a Seneca will probably have about the same glide ratio as a Bonanza. And 13-14K is pretty tolerable for a short time, especially if you pay attention to your breathing. Even if you weren't always within gliding distance of land, you'd minimize your exposure to a dunking by going that high and it would be a fairly easy climb in a Seneca.

And for the record I'm not insisting that crossing LM in a single is foolhardy, just that you need to realize that you are betting your life on a successful crossing and that with an undiagnosed engine problem in a twin your risk is higher than in a single without any recent issues.

Next time, maybe I'll take the TwinStar from UGN. It'll go high and glide better.

There ya go! This is a perfectly good excuse to fly that airplane.

 

[flyingcheesehead]

Mechanical fuel injection as it is used on aircraft, is a constant flow excess volume system feeding the servo. The positive pressure in the feed system is maintained by the "pill", a restricting orifice in the fuel return port which is post fuel usage port. If you clog the pill, the pressure at the fuel usage port increases which in turn increases the pressure and flow at the nozzles which will in effect richen the mixture. The ice can further accumulate and totally block the fuel flow to the usage port.

Henning,

Thank you. This is exactly the stuff that I really need to know, and is the most valuable tidbit on the thread so far.

 

[flyingcheesehead]

The other is between Manitowoc WI and Ludington MI and that's a bit under 44 nm.

We crossed Manitowoc to Manistee, but the two points of land are the same.

With the gear retracted and props feathered, a Seneca will probably have about the same glide ratio as a Bonanza. And 13-14K is pretty tolerable for a short time, especially if you pay attention to your breathing.

Oof. Time to buy that pulse oximeter. I've done a 4.4-hr flight where I cruised at 12,500, so probably 3 to 3.5 up that high. I can surely feel it!

When I made the same MTW->MBL hop during the summer, I filed for 9,000 and put "request climb to 13,000 at OSH" in the remarks. As soon as I was within an easy glide to MBL I came back down.

There ya go! This is a perfectly good excuse to fly that airplane.

Yup... I sure wish it was a bit closer though!

 

[Henning]

Henning,

Thank you. This is exactly the stuff that I really need to know, and is the most valuable tidbit on the thread so far.

No worries. It's funny, people think, "Huh, he shuts down for minor discrepancies, yet flies on in total crap airplanes..." The thing is, the plane has to do what I expect it to do even if it isn't "right". That people fly planes without an intimate knowledge of systems....eeesh, that's more risk than I like.

 

[jkaduk]

I don't understand the question. What is an "engine issue"? Did it quit? If so, wouldn't you have feathered and landed? Was is just running badly? Did this occur suddenly? Any engine running fine and then suddenly not running fine would be cause for investigation on the ground I would think.

 

[jesse]

Any engine running fine and then suddenly not running fine would be cause for investigation on the ground I would think.

Had that happen with a 172 last year. All the sudden the RPM's started to fall off and carb heat had no effect. I started to climb as soon as this happened and started looking for options. Finally made it to the airport now at bout 6,000 or 7,000 feet.. Spiraled down to the runway to land. Yeah climbing slowed down my arrival to this airport but I just wanted altitude so that if it did quit I'd have plenty of time to find a nice field to put it in versus chancing it staying low trying to get best speed to the airport.

No idea what caused it. After landing it coughed a few times and started to run fine. Pulled the cowling off and looked. Did a full power run up. Took off and circled the airport and climbed up high and flew it home.

 

[gismo]

Here's a brief article on the Continental FI system:

http://www.kellyaerospace.com/articles/ContinuousFlow.pdf

And for comparison this one is about the Bendix system found on most (but not all) Lycomings.

http://www.kellyaerospace.com/articles/Troubleshooting.pdf

 

[Danos]

I'm not mulitengine rated yet but I had a very similar problem in a single. I lost about 300 r.p.m. on rotation on a 3700 ft. runway and the plane sunk back onto the mains. It was way too short a strip to abort but I had enough distance to get into ground effect, build some speed and clear the treeline ahead so I did. I checked the mixture, carb heat and magneto selection, ect. and everything was where it was supposed to be. I climbed like a lead baloon to about 500 feet a.g.l. when the engine reved up and I was able to establish a normal climb out. The plane seemed fine after that. Did I turn back and get it checked out? You bet!

 

[jdwatson]

I'm not mulitengine rated yet but I had a very similar problem in a single. I lost about 300 r.p.m. on rotation on a 3700 ft. runway and the plane sunk back onto the mains. It was way too short a strip to abort but I had enough distance to get into ground effect, build some speed and clear the treeline ahead so I did. I checked the mixture, carb heat and magneto selection, ect. and everything was where it was supposed to be. I climbed like a lead baloon to about 500 feet a.g.l. when the engine reved up and I was able to establish a normal climb out. The plane seemed fine after that. Did I turn back and get it checked out? You bet!

What problem did you find when you got it checked out ?

 

[Danos]

What problem did you find when you got it checked out ?

The school claims nothing was wrong with it. My guess is it was the magneto. Needless to say I never rented it again. Since then that airplane has had an engine failure and it caught fire. It's no longer on the line.

 

[jesse]

The school claims nothing was wrong with it. My guess is it was the magneto. Needless to say I never rented it again. Since then that airplane has had an engine failure and it caught fire. It's no longer on the line.

I would look into finding a new place to rent airplanes. How many issues in other airplanes were reported by pilots where "nothing is wrong" that you don't know about?

 

[Danos]

I have. This is an issue with a lot of flight schools just out to make money. Many of these planes have problems that seem to be overlooked. On my checkride I was shooting an ILS and the glideslope started oscilating like a windshield wiper. With a safety pilot in VFR conditions fine. But I wouldnt want to be in IMC with it. It just makes you wonder what else they're letting slide. But guess this is a topic for another thread.

 

[poadeleted20]

On my checkride I was shooting an ILS and the glideslope started oscilating like a windshield wiper. With a safety pilot in VFR conditions fine. But I wouldnt want to be in IMC with it. It just makes you wonder what else they're letting slide. But guess this is a topic for another thread.

I agree, but before leaving it here, I would point out that there are a lot of things that can mess with your VOR signals. Just last week I saw the VOR needles on two separate VOR's (a Garmin 430 #1 and a Narco Mk 12E #2) acting like windshield wipers in perfect synchronization during a VOR approach -- no way that is a problem with either radio. OTOH, if the GS acts the same on different ILS's, that would lead one to believe it is the GS, not the signal.