Why do you need to turn on fuel pump when switching tanks ?

[Deb]

My boost pump quit working...I'm about 1 hour from my home field...other than the implicit risk of having no back up pump in case the engine fuel pump fails, are there any other problems with flying with an inop boost pump that I'm not aware of? I plan on taking it out once I get home and sending it for overhaul.

When we have questions like this, we think of the phrase "Working backwards from the NTSB investigation..." or "The pilot elected to... despite knowing..." Even though the risk of a failure may be small, the consequences of a failure in this case could be catastrophic. Our risk tolerance would prevent us from flying with this known airworthiness deficiency. 

[romair]

Only Jet maintenance on the field. $25/night overnight fee every night. Deb - by that reasoning you should not be able to have a ferry permit either. I think it is all about risk assessment. How risky is a 1 hour flight without a boost pump...definitely more risky than having one. I'm trying to make an informed decision

[RobertGary1]

Nope.

 

If nothing else the fact that it's not legal is an issue. Unless you have an STC that allows flight without the boost pump. 

Id pull the pump myself and replace it and just have a mechanic verify your work. Easy money for him 

Edited September 7, 2015 by RobertGary1

[RobertGary1]

I guess if you really wanted to do it and wanted it to be legal and your insurance in force you could call the fsdo and ask for a ferry permit. Might be a long shot though. But otherwise your type certificate specifies that you have a boost pump. 

[Shadrach]

I think that some FSDOs would issue a permit without much hassle provided a mechanic verifies that the failure is contained to the pump and is not a symptom of something like corrosion from having sat for 2 months with water in the fuel system.

[Shadrach]

 

If nothing else the fact that it's not legal is an issue. Unless you have an STC that allows flight without the boost pump. 

Id pull the pump myself and replace it and just have a mechanic verify your work. Easy money for him 

I just assumed he was having difficulty getting a pump right away. If it's a dukes unit, it can take a while to get ahold of. The pump itself is an easy install. Basic tools, safety wire pliers and .032 safety wire. The biggest PITA is disconnecting the pilots side nose gear door and unscrewing all of screws required to remove the panel that covers the pump.

Edited September 8, 2015 by Shadrach

[RobertGary1]

Yea I've heard that that panel is hard. I remove mine every year at annual to inspect the fuel lines. Something must be slightly different for me as I don't need to do anything with the gear door. I do use a 90 degree small driver in some places though. 

[carusoam]

Summarizing:

1) tough to get started without the pump

2) increased risk flying without the pump

3) possible insurance issue by departing with known maintenance issue

4) having a mechanic can help in a few ways...

- communicating with the FSDO for a permit to fly without

- swapping out a pump

- reviewing your installation of the pump

5) Open area at the end of the runway is better than trees and buildings

6) all the additional risk is better when you are young, when you are older, married and have kids, the risk becomes too much especially when the trees are many and large...I

7) high nose up attitude is more taxing on the pump.  FP is lower with high attitudes.

8) low nose up attitude leaves you close to the ground longer

 

did I miss anything?

best regards,

 

-a-

Edited September 8, 2015 by carusoam

[Shadrach]

Yea I've heard that that panel is hard. I remove mine every year at annual to inspect the fuel lines. Something must be slightly different for me as I don't need to do anything with the gear door. I do use a 90 degree small driver in some places though. 

 What's different is that during annual the plane is likely jacked up when you're removing it. I remove mine every year too...when the gear is retracted.

[carusoam]

I tried to add Ross additions to the list, but was unable to edit the post beyond a certain line....

like challenges to changing ou the pump include getting a replacement and jacking up the plane.

and the usual, I am a PP, not a mechanic.

best regards,

 

-a-

[jetdriven]

Only Jet maintenance on the field. $25/night overnight fee every night. Deb - by that reasoning you should not be able to have a ferry permit either. I think it is all about risk assessment. How risky is a 1 hour flight without a boost pump...definitely more risky than having one. I'm trying to make an informed decision

send me an email I can't Pm.  Bdr737@gmail.com

[pinerunner]

Well basically the SOP I was taught when getting checked out in my M20E was aux fuel pump on whenever changing tanks and whenever below 1000 ft, just to be on the safe side.  With plenty of altitude I wouldn't be afraid to change tanks without the aux pump on but I think its important to form good habits and keep them. The only reason I'd think about losing that habit would be save wear and tear on my electric auxiliary fuel pump which I've had to have rebuilt once already.

I've run a tank dry on purpose once. Had 5000 altitude and was flying in a pretty quiet area where other traffic wouldn't be a problem. I was running LOP with 8 GPH and simply switching tanks after it died got me a coughing and sputtering engine; full throttle, full rich brought it back. I lost 500-1000 ft of altitude while I was putzing around with it.

I was trained on Cessnas with gravity-feed and a both setting that you never really needed to change. Learning good fuel management habits has been a big part of my Mooney transition. Even though it seems (and is) easy, its also easy to forget, particularly at the end of a long, tiring flight, or when you get particularly busy.

 

[Shadrach]

send me an email I can't Pm.  Bdr737@gmail.com

Byron can you receive PM's? What's the deal?  Should I assume that past PMs that were not responded to were never read?

[Shadrach]

Well basically the SOP I was taught when getting checked out in my M20E was aux fuel pump on whenever changing tanks and whenever below 1000 ft, just to be on the safe side.  With plenty of altitude I wouldn't be afraid to change tanks without the aux pump on but I think its important to form good habits and keep them. The only reason I'd think about losing that habit would be save wear and tear on my electric auxiliary fuel pump which I've had to have rebuilt once already.

I've run a tank dry on purpose once. Had 5000 altitude and was flying in a pretty quiet area where other traffic wouldn't be a problem. I was running LOP with 8 GPH and simply switching tanks after it died got me a coughing and sputtering engine; full throttle, full rich brought it back. I lost 500-1000 ft of altitude while I was putzing around with it.

I was trained on Cessnas with gravity-feed and a both setting that you never really needed to change. Learning good fuel management habits has been a big part of my Mooney transition. Even though it seems (and is) easy, its also easy to forget, particularly at the end of a long, tiring flight, or when you get particularly busy.

 

500 to 1000ft? Holy Shitman! One should be able to do a full break stall without loosing 500ft.

My take on boost pumps is this. My experience is that they are fragile. We have had a few rebuilt over the years. I say with confidence that they rarely go 200hrs of actual operation (not tach time) without needing attention, often quite a bit less. I prefer to confine my use of the pump to the times that I really need it. It is tested at the beginning of each flight during start up.  If I'm going out of a short strip, with trees at the end then I use it on take off. On a 7500ft runway were I'm 1200'AGL by the time I'm over the departure end not so much.

[RobertGary1]

One issue with running a tank dry is that if the seals in your selector are still original you may still suck air from the non-selected tank. I believe lake arrow had an accident some years back due to this and as a result they told me they don't recommend flying with an empty tank. They also mentioned they've seen selectors jam. As a result I sent mine off for rebuild about 5 years ago. 

[mike_elliott]

Only Jet maintenance on the field. $25/night overnight fee every night. Deb - by that reasoning you should not be able to have a ferry permit either. I think it is all about risk assessment. How risky is a 1 hour flight without a boost pump...definitely more risky than having one. I'm trying to make an informed decision

$25/night is a whole lot less than a night in an emergency room. I am not judging you here, but reaffirming a position not to validate a risk you are considering taking when it can be avoided, which I think is what you are asking us to do.  Albeit a small risk, it can be mitigated by having it fixed before further flight. 

I would bet there is a GA a$p on a field that would charge 25/night that can fix you up. Heck, he may enjoy working on a real airplane instead of a spam can

[philipneeper]

What airfield are you at? I would help you...

[pinerunner]

One issue with running a tank dry is that if the seals in your selector are still original you may still suck air from the non-selected tank. I believe lake arrow had an accident some years back due to this and as a result they told me they don't recommend flying with an empty tank. They also mentioned they've seen selectors jam. As a result I sent mine off for rebuild about 5 years ago. 

I read about a stuck selector too. I think it was here. That really scared me. My mechanic/inspector completely inspected my gascolator at annual and I hope that means I'll never experience a stuck selector. If your seals in the selector are going bad then you maybe drawing some fuel from the wrong tank even when there's fuel in both. With fuels much higher viscosity it wouldn't be as bad as with an empty tank. I think one reason to deliberately run one dry at altitude is so that if it happens unexpectedly you'll be familiar with it. That's why I did it.

[MyNameIsNobody]

It must be tough living your life in fear that you didn't mitigate some random/unknown bit of risk out of your life...

[pinerunner]

500 to 1000ft? Holy Shitman! One should be able to do a full break stall without loosing 500ft.

My take on boost pumps is this. My experience is that they are fragile. We have had a few rebuilt over the years. I say with confidence that they rarely go 200hrs of actual operation (not tach time) without needing attention, often quite a bit less. I prefer to confine my use of the pump to the times that I really need it. It is tested at the beginning of each flight during start up.  If I'm going out of a short strip, with trees at the end then I use it on take off. On a 7500ft runway were I'm 1200'AGL by the time I'm over the departure end not so much.

The reason I lost so much altitude was that I made sure first to establish a decent glide before going for the fuel selector. It also caught me by surprise, even though I was expecting it so I lost a few seconds. I didn't retrim for a slower and slower speed but just let it maintain cruise. Then with the LOP settings it apparently wasn't as simple as turn the selector and instantly roar back to life. Consider that the fact that my engine had suddenly died means my fuel lines were all full of air so there would be some delay. Setting everything for maximum fuel flow made sense to me to minimize the time it took to get the bubbles out. I think I'll stick with the "on below 1000 ft" rule so I can minimize the chance I'll find myself trying to sort this kind of thing out close to the ground. But  maybe not just for switching tanks.

[pinerunner]

It must be tough living your life in fear that you didn't mitigate some random/unknown bit of risk out of your life...

We all die sometime so nothing to be afraid of. I just don't want to feel like a fool when I do it.

[jetdriven]

The reason I lost so much altitude was that I made sure first to establish a decent glide before going for the fuel selector. It also caught me by surprise, even though I was expecting it so I lost a few seconds. I didn't retrim for a slower and slower speed but just let it maintain cruise. Then with the LOP settings it apparently wasn't as simple as turn the selector and instantly roar back to life. Consider that the fact that my engine had suddenly died means my fuel lines were all full of air so there would be some delay. Setting everything for maximum fuel flow made sense to me to minimize the time it took to get the bubbles out. I think I'll stick with the "on below 1000 ft" rule so I can minimize the chance I'll find myself trying to sort this kind of thing out close to the ground. But  maybe not just for switching tanks.

All the more reason to get comfortable running tanks dry. For the average "I'll never run a tank dry" pilot, when it does actually happen can be quite a shock, like here. If it happens near the ground, an accident could result.  For those of us comfortable with the procedure, its a non-event. At any rate, if you know just how much fuel each tank holds and how much you are burning, its easy to switch with a gallon or less left, and be reasonably sure all the other fuel is in the other tank.

[jetdriven]

Byron can you receive PM's? What's the deal?  Should I assume that past PMs that were not responded to were never read?

Inbox full. I have deleted a lot of stuff but it still shows full

[mike_elliott]

 

 

It must be tough living your life in fear that you didn't mitigate some random/unknown bit of risk out of your life...

If this comment is relating to my post, I assure you it is not tough living my life knowing I attempt to mitigate all risks to my life that I possibly can. In fact, I find it quite comforting and teach this. I don't launch on one operable mag either. Same difference, imo.

"If there is a question, the answer is no"  This philosophy has served me well over the years, and bit me when I have tested it.

[RobertGary1]

All the more reason to get comfortable running tanks dry. For the average "I'll never run a tank dry" pilot, when it does actually happen can be quite a shock, like here. If it happens near the ground, an accident could result.  For those of us comfortable with the procedure, its a non-event. At any rate, if you know just how much fuel each tank holds and how much you are burning, its easy to switch with a gallon or less left, and be reasonably sure all the other fuel is in the other tank.

But it may be good to send your selector off to Lake Aero to be rebuilt before hand. There is no way to inspect the seals on the selector in the field so jamming or pulling from the empty tank can happen. I believe there was a real engine out that resulted from pulling from the non-selected tank after running a tank dry.

 

-Robert