Changing tanks on the PA 28

[Justin_85_Hants]

Hi,

Sorry if this question has been asked before! I'm changing over to the PA28 after flying the C152 and I am unsure on the procedure for changing fuel tanks both on the ground and in the air? Whilst in the air should the fuel pump be switched on prior to and whilst changing the tanks? Also, at what stage after takeoff do you normally turn the fuel pump off? Thanks

Justin :ugh:

[cjhants]

hello and good luck with the PA28
i normally turn off pump at 1000ft, and watch fuel pressure guage to make sure there is no drop. turn pump on again when airfield in sight.
always turn on pump before changing tanks, and again watch pressure guage after turning off.
cheers
CJH

[Final 3 Greens]

Justin

On the ground, you can just change over without using the electric fuel pump, BUT never change tanks on the ground after you have finished your power checks, since there is enough fuel in the gascolator (fuel bowl) to get to about 200ft before your engine stops, if you have a problem with the fuel flow form the new tank.

Check the POH for the altitude to switch off the electric fuel pump, IIRC it is not below 300ft, but no harm on leaving on for longer.

In the air, as you suggest, always switch on the electric fuel pump and check that the fuel pressure is in the green, then switch tanks and monitor the fuel prerssure, switch off the pump, monitor the fuel pressure until you are sure all is okay.

[hingey]

I use pump off for power checks to see the engine won't cut if it isn't used. But as 3greens says, don't change between power checks and take off. I usually leave the pump on until the top of the climb (unless I'm heading quite high!) and off with the top-of-climb check.

Also I wouldn't recommend changing with unnecessary frequency i.e. every FREDA check. I think Piper recommend (on long flights) running one tank for an hour, using the other for 2 hours, then back to the other for another hour.

I may stand to be corrected.

h

[Readability5]

Turn on for starting and then off for taxying until the check list requires it for power checks. The period when the electric pump is off confirms that the engine pump is working.
Generally follow the same rule in the air. Use the electric fuel pump for climbing or descending, changing tanks and always use for approach and landing. I also use it for procedures such as steep turns and stalls. Leaving it off for the rest of the time means that you'll pick up on an engine pump failure immediately.
Turning off the fuel pump at 1000 feet doesn't give you many options if you do have a problem. I tend to leave the pump on until top of climb leaving plenty of options if a problem arises.
The fuel pump should also be one of the first things to consider switching on if the engine starts running rough or there is a loss of power in flight.
Also consider when you should have the fuel pump firmly off, such as engine firm on start or take off.
Have a look at the POH. Probably the emergency and normal procedure sections.
I learnt on a 152 and have flown a PA28 since getting my licence and now own a share in one. They're great and you'll love it.

[172driver]

Despite my 'nom de plume' I did my PPL on PA28s (Warriors and Archers).

Haven't flown one in a long time, but remember what my instructor drilled into me about changing tanks:
Visualize the fuel selector as the face of your wristwatch and set the fuel to wherever the minute hand is. In other words, change tank every 30 mins or so. This way you can never run one tank dry and have fuel in the other one. Also eliminates uncertainties of the 'when did I last switch tanks' type. Of course assumes you are wearing an analogue watch....

Other than that I'll second the comments above re not switching tanks after runup.

[MyData]

F3G

On the ground, you can just change over without using the electric fuel pump, BUT never change tanks on the ground after you have finished your power checks, since there is enough fuel in the gascolator (fuel bowl) to get to about 200ft before your engine stops, if you have a problem with the fuel flow form the new tank.

A new one for me, and makes perfect sense. One I shall now remember going forwards and make a note of on my check list. Not that I've been in the habit of changing tanks at such a late stage.

Yet another gem of information from the forums of PPRuNe.

[stevef]

As an engineer, I sometimes shut the engine down by using the fuel selector instead of the mixture control. On a couple of occasions this has revealed a faulty valve. Two reasons: obviously vital in the event of an engine fire or forced landing after engine failure and secondly, saves flooding the hangar floor when removing the fuel filter!

[Final 3 Greens]

My Data

Thanks for your comments - I saw this happen many years ago, although fortunately the PA28 managed a perfectly good forced landing straight ahead and was later flown out of the farmers field following an engineering check. It was horrifying to hear the crash alarm go off and see the fire service reacting with blues and twos.

Just another thought on how often one should change tanks.... In the states a PA28 driver had loads of fuel on the left and decided to drain the right tank (I can't remember the reasons why.)

Unfortunately, when he went to change tanks, the selector knob came off in his hand :\

Immediate forced landing required and made safely, but it does make you think about whether you have enough fuel, in the tank in use, to make an approach and landing at your nearest option.

[combineharvester]

Hello, the checklist i follow states:

Start Up & Taxi: Tank with lowest contents.
Prior to Power Checks: Fullest tank
Fuel Pump on after power checks, during pre-take off vital actions.
Fuel pump off above 1000'
Fuel pump on for tank changes (i teach every 1/2 hour at least on a long nav ex)
Fuel Pump on below 1000'

Hope this helps

[172driver]

When I converted from 150/152 to PA28's I took one of those mechanical (wind-up) kitchen timers with me, and set it to go off after 30mins so I wouldn't forget to change the tanks.
PD

Without wanting to wind you up ;) I think my wristwatch method is slightly easier !

[fireflybob]

Lots of good and well intentioned advice here but I am disappointed to note that nobody has made any reference to what is specified in the relevant Flight Manual/Pilot's Operating Handbook which is part of the C of A for the aircraft - surely this definitive docuement should be the first port of call when there is doubt concerning the operation of the aircraft and it's systems rather than relying on "hearsay".

Interestingly the PA28 Flight Manual I have specifies leaving the electric fuel pump on (after take off) until levelling out at the first cruise level.

[theresalwaysone]

Be careful with just quoting a 1000 feet. What you mean is a 1000 feet above a surface suitable for a re- landing/alightment. That may not coincide with the 1000 feet on your altimeter ! Take a 1000 feet AGL/AMSL as a minimum-you may want to extend that depending on your experience and the terrain/water you are flying over. For instance if I was taking off over ground with a very marginal chance of a re-land I would be keeping that pump on for a much longer time.

In a single engined aircraft you need to be even more respectful of the fuel and the fuel systym.

1. Are you sure of the integrity of the source of the fuel?
2. Are you sure the fuel is not contaminated in the tanks(I would never fly a s.e. a/c without checking a fuel sample myself and on occasions when i do not like the look of the bowser eg The Arthur Shagnasty bought on Ebay bowser, I would check again after settlement)
3. Proove the integrity of the electric pump BEFORE start, remember thats the best place to initially check it--turn the pump on, listen and watch that FP gauge.
4. Check each tank delivers fuel to the engine, a momentarily change wont proove it, you need to clear the fuel in the line from the original selected tank first.#

I would advise you not to rely on a checklist to tell you to do critical items (as suggested in other posts) With single pilot operations and critical simple actions, a checklist should be the second check that you have done the action. At the holding point you should complete the critical memory items that will minimise an incident at what is the most critical point in the flight, the take off and initial climb out--that would also of course include a simple self brief of what you are going to do if the engine stops at 50 - 500 feet, sadly never considered by most light a/c pilots.

This critical point means on the PA28 you now want to prove the integrity of the remaining tank and as this is the tank you are pinning your pension on-- BE SURE. as someone has already said get it on before the run up, give it chance to be exclusively feeding the engine.

I personally would start the engine on the tank already selected(not having moved the selector) if it starts and runs on this tank i know its ok-then change tanks and taxy, i want to spend the longest time on the tank i am pinning the pension on--get my meaning!

I remember a case many years ago where a smart arse jumped in and didnt select the fuel on he went straight out and he managed to get airborne to about 100 feet before the engine stopped. It was his own strip you see--no delay and coupled with the fact he was a cowboy, an accident waiting to happen. my point being there is quite a bit of fuel in the line between tank an engine

There are all sorts of combination for balancing tanks in the air. What you want to consider before changing tanks on a single is where you are. Would you for instance consider it better airmanship to clear the city you are crossing before changing tanks or get to the land before changing tanks on a sea crossing-- this is where learning to fly by numbers dosnt work. Knowing why you need to do things and what you are trying to achieve makes for a better pilot. The classic example is the circuit, what most instructors teach is climb straight ahead to 500 feet after take off now thats learning to fly by numbers because if the engine stops a couple of years later down the line at 500 ft and you lower the nose to find the Nelson Mandella council estate you will remember what I said. " For take off in a SE a/c select the path that will give you the safest re-landing path/area in the event a serious engine malfunction."

Consider that turning the fuel pump off may well stop the engine immeadiately so again dont just fly by numbers ask yourself in regard to terrain and making a safe forced landing is this the best place/altitude to stop the engine!

When running tanks towards empty alway try and manage the last tank so that enough will remain for say at least 15/20 mins flight, because if you ever get caught out, say the weather is bad or you have got lost or something has happened to divert your attention away from normal operations you may find that you forget other normal routines such as changing tanks etc, imagine running out of fuel on finals and you change tanks to find the other one is empty too.

So base your mangagement on leaving a reserve in one tank, with regular balancing to achieve this--the balance isnt critical, keeping the engine running is!

Safe flying

[theresalwaysone]

Firefly Bob has just made a very good point here, always go to the makers manual note i said MAKERS, not the Hemaroid School of Flying interpretation of the manual, as I think some are quoting here.

Its a bit like the advice you get on here, its opinion and more worringly you have no idea of the experience,ego or calibre of the person giving it and yes that includes me!

[Martin @ EGLK]

Personally, I always have the pump on when changing tanks. And I keep a brief eye on on the presures while doing so.

I also make sure that both tanks have been used while on the ground both with & without the pump.

As for when to change tanks: If I'm flying over the sea, I set the engine up just before the coast & leave it as much as poss. This means that I don't change tanks. Another time I never change tanks is from the approach phase to an airfield till I'm parked. But I'll quite happily change whenever I remember my FREDA's.

And I'll take a bit of a tip from theresalwaysone. I've never really considered what's underneath me when I change & where I can park if the cooling fan stops.

[bmoorhouse]

Had a useful tip from our CFI for changing tanks (once in the cruise and taking into account crossing water, built up areas etc)

Use the minute hand of your watch - if it points to the left (i.e. between 31 minutes and 60 minutes - use the left tank and if it points to the right (1 minute to 30 minutes) use the right tank.

Means you will regularly cycle between left and right every half hour or so.

Personally I always turn on the fuel pump before changing tanks and then off again whilst checking the fuel pressure.

As has been said above NEVER change tanks after power checks until you are confident you can glide to an acceptable landing site. I usually come "off pump" when leaving the circuit, and "pump on" when rejoining.

[Justin_85_Hants]

Hey,

Thanks everybody for the really useful comments! I'm clear on the use of the fuel pump, thanks again.

Justin

[Final 3 Greens]

Firefly Bob has just made a very good point here, always go to the makers manual note i said MAKERS, not the Hemaroid School of Flying interpretation of the manual, as I think some are quoting here.

Be very careful. Some flying schools who operate PA28s have CAA approved in house manuals and checklists, which are part of the C of A.

[Johnm]

Firefly Bob has just made a very good point here, always go to the makers manual note i said MAKERS, not the Hemaroid School of Flying interpretation of the manual, as I think some are quoting here.

Be very careful. Some flying schools who operate PA28s have CAA approved in house manuals and checklists, which are part of the C of A.


This is sound advice. The POH recommendations on my Archer 2 are as follows:

In start up phase use electric pump to pressurise the fuel system, then switch it off and prime the engine

After taxi but before power checks change tanks, this should ensure that both tanks get checked on the ground as well as the fuel cock.

Fuel pump on for take off and off not below 1000ft AGL or when settled in the cruise. If climbing high you might want to switch off in the climb because the pump is not designed for continuous use, it's an auxiliary back up pump. Obviously check fuel pressure before and after, there shouldn't be a significant drop in pressure.

I change tanks every half hour or at the half way point of a trip if it's an hour or less. If going over water I try to time things so I change tanks just before coasting out and then leave it until coasting in. Fuel pump on before change and off after with a pressure check each time.

If you are a regular PA28 pilot (or PA32 for that matter) it soon becomes second nature.

[Readability5]

Lots of good and well intentioned advice here but I am disappointed to note that nobody has made any reference to what is specified in the relevant Flight Manual/Pilot's Operating Handbook which is part of the C of A for the aircraft -
Sorry FFB - but the POH was referred to as far back as the third post and I went as far as pointing Justin at 2 specific sections in post 5.
I agree about checklists - they tend to be the owners interpretation of the POH and should be followed with care. The key thing is to think about what you're doing, rather than doing it because an instructor told you. I re-thought the "fuel pump off at 100ft" after a friend in a Seneca switched them off at 1000ft only to lose an engine - and he had an instructor with him.
I guess the moral of the story is to make your instructor earn their money. Think about why you're doing things and question the instructor - if he knows his stuff he'll be happy to explain.

[fireflybob]

Readability5, thanks for the correction and my apologies - I had not noticed that!

However, my basic comment stands that we should be consulting the POH/Flight Manual FIRST, rather than relying on hearsay or other peoples "opinions" on how the fuel system (or anything other system on the a/c come to that) should be operated.

My experience is that some FTOs do not emphasise the importance of the POH/Flight Manual (and there is a legal requirement that, as pilots, we are aware of these documents AND any amendments prior to flight), indeed such documents are often hidden away somewhere!

Some of the so-called "checklists" on the market are also, in my opinion, quite abysmal and full of inacurracies!

[IO540]

I agree re generic checklists sold by pilot shops - avoid them.

One should always read the actual POH as a first place to look.

However, there is more to the electric fuel pump than meets the eye. Most low wing planes have it after the fuel tank selector valve. I therefore don't see why turning it on (as I have been religiously doing for 5 years) around changing tanks should make any difference. It isn't going to pressurise the pipework in the valve; in fact it will reduce the pressure at that point.

[Final 3 Greens]

IO540

I don't have a PA28 fuel diagram to hand, but IIRC one of the key aspects is that the electric fuel pump is on a loop that circumvents the mechanical fuel pump.

So its providing redundancy in case the mechanical pump fails and blocks the system. Don't know about other types.

WRT to POH, yes, BUT (a very big but), they are only as good as the updating process.

Older PA28 POHs may not have updated - e.g. SB753 giving expanded spin recovery techniqes for the PA28-140.

Also, are you entirely happy with the POH checklists, e.g. the approach to using carb heat in some sircraft? A bland "carb heat check" downwind recommendation is ambiguous and may mean (in Arizona) a quick look, whilst in Florida it may mean the sustained application in high RH and elevated temperatures. Slavishly following the POH and leaving the carb heat on long enough to see rpm drop and recovery could be a pretty bad thing to do.

So, yes I do agree that the POH should be consulted, but equally believe that good airmanship dictates that the pilot ensures that POH configuration management is effective and that the POH is interpreted intelligently.

[IO540]

I agree; in fact I did my own checklist from the POH and then adding avionics-specific stuff.

I don't think there is (normally) a bypass on the mechanical fuel pump. Unless the mech pump is a gear pump (or some other positive displacement type) if its drive shaft should shear off then you can still push a liquid through it, and that's what I understand the electric pump would do.

However a common "selling point" of using the electric pump around tank changeovers is to pressurise the pipework and prevent the formation of bubbles. This I don't understand; the electric pump is normally in the wrong place for that.

[Final 3 Greens]

I don't think there is (normally) a bypass on the mechanical fuel pump.

I think that there is an the PA28, but unfortunately I don't - have the diagram to hand, so I may be wrong in my assertion.

I can visualise a schematic loop around the mechanical pump, but then again the brain does a wonderful job of convincing you that you saw what you wanted to see ;)

The "bubbles" in the fuel line seeling point (vapour lock?) is an interesting one, but I've never encountered that in a PA28 - IIRC the boost pumps in some Beech's are mandadted for that purpose under certain conditions (high temp.)

Your point about adding avionics to the checklist is an interesting one that I hadn't considered.

As we see more advanced kit in the GA fleet, a simple and generic "radio on, transponder to standby" clearly won't cut the mustard anymore and the aftermarket nature of much kit clearly means that the POH will not reflect what sits in front of the pilot,

[smarthawke]

Just a couple of technial pointers. The PA28 fuel system is one long line from fuel selector through the pumps to the carb. If the mechanical fuel pump fails (it's a diaphragm pump, by the way) then the elctric pump will still feed fuel through the mechanical pump.

[DFC]

In general, the electric fuel pump needs to be on at any time there will not be suficient time for the mechanical pump to fail, you to realise and turn on the electric one and for fuel to start flowing again.

Most PA28s use the figure of 1000ft AGL as a starting point.

To say that one would have the electric pump on when flying over a built up area in case the mechanical pump failed and a forced landing would be required in the built up area seems to miss the point that one must be high enough on such a flight to glide clear regardless of the reason why the engine could fail!

Having the electric pump on when changing tanks means that it is already running so if you select an empty one then switching back to the one with fuel can be done straight away cause the electric pump is already running and things should be restored quickly.

Another reason for turning on the electric fuel pump in some aircraft is the reduction in engine power at high altitudes. The higher one flies, the less power the engine produces and the less power available to drive the engine accessories such as the mechanical fuel pump. Some aircraft require the electric pump to be on at such altitudes to ensure adequate fuel flow.

As previously mentioned, read the POH.

Regards,

DFC

PS, A Local "flight manual" (for want of a better term) produced by say a club will not form part of the C of A unless the CAA (EASA) and the Type Certificate Holder agrees to the document. That is why all the CAA supplements one finds in Piper Manuals are written by the CAA but put there by Piper.

Such a local manual would normally be part of the operations manual and have the same weight.

[theresalwaysone]

This is sound advice. The POH recommendations on my Archer 2 are as follows:

In start up phase use electric pump to pressurise the fuel system, then switch it off and prime the engine

After taxi but before power checks change tanks, this should ensure that both tanks get checked on the ground as well as the fuel cock.

Fuel pump on for take off and off not below 1000ft AGL or when settled in the cruise. If climbing high you might want to switch off in the climb because the pump is not designed for continuous use, it's an auxiliary back up pump. Obviously check fuel pressure before and after, there shouldn't be a significant drop in pressure.

I change tanks every half hour or at the half way point of a trip if it's an hour or less. If going over water I try to time things so I change tanks just before coasting out and then leave it until coasting in. Fuel pump on before change and off after with a pressure check each time.

If you are a regular PA28 pilot (or PA32 for that matter) it soon becomes second nature.

This repeat of everything thats been said sums it all up

[theresalwaysone]

To say that one would have the electric pump on when flying over a built up area in case the mechanical pump failed and a forced landing would be required in the built up area seems to miss the point that one must be high enough on such a flight to glide clear regardless of the reason why the engine could fail!

I didn't miss the point DFC but a lot of SE pilots do fly over built up areas areas where it is unlikely they would be able to glide clear in the event of an engine failure, the area below the Birmingham CTA around the North of Birmingham being my local example. Low flying has, and I suspect always will be, one of the most common infringements of the ANO.

[Fduarte]

Anyone thought of reading the aircraft operations manual before ever flying?
It's all there!
Google it! :8

[Final 3 Greens]

Fduarte

If you google it it isn't the aircraft flight operations manual.

So there :=

[Fduarte]

I meant: There's allways a book that comes with a plane!

Good safe flights for you all!:)

[bookworm]

In general, the electric fuel pump needs to be on at any time there will not be suficient time for the mechanical pump to fail, you to realise and turn on the electric one and for fuel to start flowing again.

With you all the way so far...

Having the electric pump on when changing tanks means that it is already running so if you select an empty one then switching back to the one with fuel can be done straight away cause the electric pump is already running and things should be restored quickly.

So why is the mechanical pump likely to fail at the very moment you change tanks? As long as it doesn't, even if the engine is starved of fuel, the engine will still turn, delivering fuel as soon as you select a full tank again.

[jabberwok]

Just a couple of technial pointers. The PA28 fuel system is one long line from fuel selector through the pumps to the carb. If the mechanical fuel pump fails (it's a diaphragm pump, by the way) then the electric pump will still feed fuel through the mechanical pump.

What's the extra pipe for then?

http://www.homepages.mcb.net/bones/WebPix/PA28Fuel.gif

[Tinstaafl]

In case the EDP failure results in a line blockage within the EDP.

[jabberwok]

So if the electric pump is on then is it feeding fuel through both pipes or just through the bypass?

[Final 3 Greens]

Thanks for posting that diagram Jabberwok, I thought my memory was going.

[Zulu Alpha]

Why not leave the electric pump on all the time?

Only problem is spotting whether either pump has failed, on a fuel injected engine you need to prime, so this checks the electric pump is working.

[White Bear]

Not PA28 related, but about fuel pumps;
My Cardinal POH says to turn the fuel pump on during run up and check for increased fuel pressure, then turn it off. It then fails to mention it again.

Regarding fuel pressure when running both pumps, I notice on my aircraft the pressure increases by 3-4 lbs. My point is: does increased fuel pressure affect the air/fuel ratio particularly on carbureted engines? Is it possible that increased fuel pressure could overwhelm the float valve and allow a higher fuel level in the float bowl, and therefore a richer mixture. (Unless there is a pressure relief valve in the system somewhere, then of course, no fuel pressure increase would be seen).

I seem to remember a Bonanza accident that was attributed to the pilot’s failure to turn OFF the electrical fuel pump after takeoff, causing the engine to run rich on part throttle, rich enough in this case to cause the engine to die, and he crashed, killing himself. Apparently this is known issue with Bonanza’s, my question is, is it an issue with all aircraft, or only with fuel injected engines?
Regards,
White Bear.

N.B. I am very well aware of how carburettors work, so those who might feel the need to explain to me the basics, please refrain from doing so.

[gasax]

In theory keeping both pumps on will have no effect on the fuel / air mixture. The float assembly and its valve, control the level of fuel in the bowl keeping it near constant and so the supply side does n't matter so long as it can keep up.

However (there always is one!) that depends on the float having enough bouyancy to drive the valve shut against the supply pressure so there must be some supply pressure which can overwhelm the valve - but that is probably a fair bit higher than the pumps can produce.

Of course if the float valve is worn then it may 'leak' with the extra pressure and that would raise the level in the float chamber and richen the mixture, considerably richening the mixture if the float chamber is filled, however this is probably only possible at lower power settings. ( a problem my lawnmower has at the moment when stopped - allowing fuel into the crankcase on the mower, but with an updraft carb in an aircraft onto the ground.)

[Pronto]

My Data

Thanks for your comments - I saw this happen many years ago, although fortunately the PA28 managed a perfectly good forced landing straight ahead and was later flown out of the farmers field following an engineering check. It was horrifying to hear the crash alarm go off and see the fire service reacting with blues and twos.

Just another thought on how often one should change tanks.... In the states a PA28 driver had loads of fuel on the left and decided to drain the right tank (I can't remember the reasons why.)

Unfortunately, when he went to change tanks, the selector knob came off in his hand :\

Immediate forced landing required and made safely, but it does make you think about whether you have enough fuel, in the tank in use, to make an approach and landing at your nearest option.



My old club, where I flew for 15 years, had four Warriors (of varying models, specifications and ages) and an Archer. I flew each of the Warriors at one time or another. In the POH for one of these aircraft (and I can't remember which one) there were a few lines of advice on changing tanks. If I recall it correctly, Piper's advice was to run the engine on one tank for 30 minutes, then change to the other and run it dry. Then turn back to tank one ... . Maybe following that advice is what got to subject of Final 3 Greens' story into trouble?

When I checked out on a Warrior (after doing my training on a C152), I was advised to change tanks every 30 minutes: fuel pump on first, and run the pump for two or three minutes after the change before turning it off. It's worked for me for 15 years or so!

P