switch tank, boost pump ON ?

[Guest]

From the K model maintenance manual.

Clarence

[GeeBee]

Another reason to switch tanks before TOD for landing.

 

[A64Pilot]

8 hours ago, Ulysse said:

Not switching tanks during downwind is new to me. It has been part of my training for PPL and I have done that for many years: we have an equivalent of the american GUMPS which includes switching tank. I guess I will do like many have suggested: switch at top of descent.

 

I think we were all trained the same way, but most of our training was in the pattern and or at relatively low altitude, very little actual traveling at altitude. Training is meant to replicate real life, but sometimes doesn’t. Plus all my airplane training was done by kids with far fewer hours than I had, of course they went strictly by the syllabus.

Over the years I have gotten so I don’t switch tanks all that often anymore, I think initially I was taught switch tanks every 30 min or something, Lord knows why. Now if the flight is  a 1.5 hour trip I won’t switch at all, until before I return, then I’ll switch on the ground.

‘Having the fuel selector handle come off in my hand changed things for me, it was my Maule and had the Cessna type selector, one screw holds the lever on, and obviously it had loosened. Usually I didn’t actually hold the thing, just push it so if it came off as I wasn’t holding it, it would drop of course, that day for some reason I had enough hold on it so it didn’t drop, luck was with me. On the Maule it was on the left kick panel, under your knee.

[GeeBee]

I think "fuel" at TOD comes from multi-engine airplanes, because on most, you want to terminate any cross-feeds prior to starting down. On many transport jets you want to make sure the fuel has transferred from the tail. I have "fuel" on my descent checklist, but if a switch is necessary, I do it within gliding range of something that I can land on.  I also don't get myself into a situation where I cannot land on the selected tank, in case the fuel selector fails.

 

[PT20J]

1 hour ago, A64Pilot said:

I think we were all trained the same way, but most of our training was in the pattern and or at relatively low altitude, very little actual traveling at altitude. Training is meant to replicate real life, but sometimes doesn’t. Plus all my airplane training was done by kids with far fewer hours than I had, of course they went strictly by the syllabus.

Over the years I have gotten so I don’t switch tanks all that often anymore, I think initially I was taught switch tanks every 30 min or something, Lord knows why. Now if the flight is  a 1.5 hour trip I won’t switch at all, until before I return, then I’ll switch on the ground.

‘Having the fuel selector handle come off in my hand changed things for me, it was my Maule and had the Cessna type selector, one screw holds the lever on, and obviously it had loosened. Usually I didn’t actually hold the thing, just push it so if it came off as I wasn’t holding it, it would drop of course, that day for some reason I had enough hold on it so it didn’t drop, luck was with me. On the Maule it was on the left kick panel, under your knee.

I’ve heard so many stories about fuel selectors going wrong that I kind of hate touching the darned things. I always worried about it in the Beaver because the instrument panel-mounted selector is connected through cables and pulleys to the actual valve aft of the rear belly tank. But, the Canadians built them pretty tough. A friend had the screw that attaches the handle back out and jam the selector between left and right on a Cherokee. 

Skip

[Vance Harral]

I appreciate the replies about the Continental fuel system setup.

I remain of the opinion that the design is not great.  Statements like, "It's not that complex once you get used to it, but many people do it wrong anyway"; and, "I don't know why mechanics can't correctly follow the maintenance manual procedure", make my engineering spidey sense tingle.  I've learned in my career that when people keep messing up a procedure you've carefully documented, and you find yourself increasingly frustrated that they can't follow what you think are simple directions... it's generally a clue that your system is at fault, not the people operating it.

[ArtVandelay]

I’ve heard so many stories about fuel selectors going wrong that I kind of hate touching the darned things.

I switch once, about halfway and do it either over an airport or suitable place to land. Mooney handles the fuel imbalance just fine, I always burn off the left tank first.

[A64Pilot]

4 hours ago, Vance Harral said:

I appreciate the replies about the Continental fuel system setup.

I remain of the opinion that the design is not great.  Statements like, "It's not that complex once you get used to it, but many people do it wrong anyway"; and, "I don't know why mechanics can't correctly follow the maintenance manual procedure", make my engineering spidey sense tingle.  I've learned in my career that when people keep messing up a procedure you've carefully documented, and you find yourself increasingly frustrated that they can't follow what you think are simple directions... it's generally a clue that your system is at fault, not the people operating it.

About your only option though is to educate yourself on it, and or acquire the tools etc and “assist” your A&P in setting it up correctly. It’s an involved process and I think people take short cuts, and or simply check take off fuel flow and cal it good.

‘If I were an owner, I think I’d take it to an engine shop thats familiar with it, and have them perform the SB, or SID or whatever it is. 

[A64Pilot]

Ag plane I used to build had no fuel selector, it had an on and off fuel valve, but both tanks fed a rather large as in 5 gl or so header tank. Two fuel lines from each tank one fwd and one aft so no matter what attitude you were in you couldn’t unport the fuel, and if you managed somehow, you still had that 5 gls in the header tank.

‘I still don’t see the need in switching tanks, I like aircraft where “both” is an option.

‘Some aircraft are ridiculously complex. I wanted a Meyers 200D, they have four tanks, each have to be selected, there is one fuel quantity indicator, it reads the selected tank.

[GeeBee]

19 hours ago, Vance Harral said:

I appreciate the replies about the Continental fuel system setup.

I remain of the opinion that the design is not great.  Statements like, "It's not that complex once you get used to it, but many people do it wrong anyway"; and, "I don't know why mechanics can't correctly follow the maintenance manual procedure", make my engineering spidey sense tingle.  I've learned in my career that when people keep messing up a procedure you've carefully documented, and you find yourself increasingly frustrated that they can't follow what you think are simple directions... it's generally a clue that your system is at fault, not the people operating it.

I'll say this. I've never had a Continental injection system quit. I have had two Bendix systems quit on Lycomings, one resulted in a dead stick landing. Another case I know of, killed a friend of mine. The Bendix RSA system is very simple, but it is that simplicity that makes it fault intolerant. One pin hole in one of the two diaphragms and it quits.

 

[CharlesHuddleston]

I must say, on our 1982 K, I never have never had the need (knock on wood) to touch the low boost. On the occasion that I did bump it accidentally, it almost stalled the engine. Having said that, I do not use it with swapping tanks, ever. I also will swap tanks (if needed) when I begin to descend. Love, love, love my K.

[carusoam]

For comparison…

The IO550 has a HI and a LO boost switch…

The low can be used to prime, and run with the engine for a really cold start… until warm enough to continue on its own…

The high is used often to prime in 5 seconds instead of 15…

 

The M20K has the most complex plumbing for its fuel pump system…. Know which version you have… as there has been an update from first to last…

PP thoughts only, not a mechanic…

Best regards,

-a-

[steingar]

On 7/2/2021 at 4:05 PM, sleeper-319 said:

I don’t want to dissuade you from self care, but if you’re after a better solution, our club has a homemade switcher made out of a small length of PVC pipe with a notch cut in once end that fits nicely over the the fuel selector. It’s a game changer for Mooney’s with the tank selector where yours is.

I can take a pic and post it later today, but basically it’s this… a 12” length of 1” schedule 40 PVC. One end has two notches cut in it to fit over the selector, and the other end has a hole drilled through about a half inch from the end, with a 2.” long 1/8 in bolt through it to act as a sliding T handle. It’s simple and effective and sits in the right seat seat back pocket when you’re not using it. 

You would deny me carnal experience?  You bad man!

My ministrations to change fuel tanks are inconvenient, but not terribly difficult.  Were I wider in girth they might not be, indeed a very good motivation to increase the rate of my decrease.  Last thing I want is yet another widget to keep track of in my cockpit, however.