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Electric fuel pump cycling

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gjgiesler(at)hotmail.com
Guest

Posted: Sat Apr 05, 2008 7:17 am Post subject: Electric fuel pump cycling

Question

  

   Before starting the engines i am hearing a pulsing relay clicking that continues even after the flaps are retracted.The hydraulic pressure needle is twitching around 600psi as it makes this noise. If I step on the brakes the pump will work continuous untill just short of redline. After the brakes are released the pressure drops back to six hundred and the clicking relay sound comes back. Have I just never noticed this untill now, I have owned 500RX for a year, or is this a problem ?

  

                                                                                                             Gary

                                                                                                              500RX--1974 500S

Use video conversation to talk face-to-face with Windows Live Messenger. Get started!  [quote][b]

dfalik(at)sbcglobal.net
Guest

Posted: Sat Apr 05, 2008 12:54 pm Post subject: Electric fuel pump cycling

Gary,  

   

I am certainly no expert, but I have owned a 500S for 3 ½ years.  It is the electric hydraulic pump that you hear as it try sot maintain the 600 lbs. in the system prior to the start of an engine.  At that time, the engine driven pump produces around 1000 lbs.  If the engine is running and the gauge only shows 600 then it indicates a major loss of hydraulic fluid or both pumps are not working.  

   

It the flap lever is not in the totally off position then I have had the same symptoms that you are having.  Sometimes it is difficult to feel the total off position of the flap handle as the detent is not that noticeable.  

   

I am sure others with many more years of experience will chime in an we will all learn from it.  

   

Don  

   

--

gjgiesler(at)hotmail.com
Guest

Posted: Sat Apr 05, 2008 6:27 pm Post subject: Electric fuel pump cycling

Don.

        When the engines are driving their pumps the psi is around 1000. And the needle is not twitching , I cant tell if the clicking relay sound is there or not because of the noise. I will experiment with finding the flap " OFF" detent......didn't know there was one.

                                                                 Thanks

                                                                             Gary      500RX

________________________________

[quote] From: dfalik(at)sbcglobal.net

 To: commander-list(at)matronics.com

 Subject: RE: Electric fuel pump cycling

 Date: Sat, 5 Apr 2008 16:51:19 -0400

 

 

 Gary,

 

 

 

 I am certainly no expert, but I have owned a 500S for 3 ½ years.  It is the electric hydraulic pump that you hear as it try sot maintain the 600 lbs. in the system prior to the start of an engine.  At that time, the engine driven pump produces around 1000 lbs.  If the engine is running and the gauge only shows 600 then it indicates a major loss of hydraulic fluid or both pumps are not working.

 

 

 

 It the flap lever is not in the totally off position then I have had the same symptoms that you are having.  Sometimes it is difficult to feel the total off position of the flap handle as the detent is not that noticeable.

 

 

 

 I am sure others with many more years of experience will chime in an we will all learn from it.

 

 

 

 Don

 

 

 

 --

tylor.hall(at)sbcglobal.n
Guest

Posted: Sat Apr 05, 2008 7:12 pm Post subject: Electric fuel pump cycling

Gary,

You want to hear the hydraulic pump and see 600 psi on the gauge  

before you start the engines.  If the engine starts and you have no  

pressure, it will roll forward unit the engine driven pump can pump up  

enough pressure to make the breaks work.  Rolling forward when you do  

not want to can be a problem of running into something.



In the older 560/680, there is a hand pump that needs to be pumped up  

to set the breaks.



Are you aware that you can pull the circuit breaker on the electric  

hydraulic pump after you take off?



If you have a hose failure in flight, the electric pump will attempt  

to keep the pressure up and pump all the hydraulic oil through the  

broken hose?  There is a reserve amount in the hydraulic tank that  

would allow you to stop the aircraft is you land and push in the  

circuit breaker to make the breaks work.  It would be a no flap landing.



When was the last time you inspected all the hydraulic hoses?  It is a  

problem of aging aircraft.



Just a thought.



Tylor Hall

On Apr 5, 2008, at 8:25 PM, Gary Giesler wrote:



[quote] 

 >

 Don.

        When the engines are driving their pumps the psi is around  

 1000. And the needle is not twitching , I cant tell if the clicking  

 relay sound is there or not because of the noise. I will experiment  

 with finding the flap " OFF" detent......didn't know there was one.

                                                                 Thanks

                                                                             Gary 

       500RX

 ________________________________

> From: dfalik(at)sbcglobal.net

> To: commander-list(at)matronics.com

> Subject: RE: Electric fuel pump cycling

> Date: Sat, 5 Apr 2008 16:51:19 -0400

> Gary,

>

> I am certainly no expert, but I have owned a 500S for 3 ½ years.   

> It is the electric hydraulic pump that you hear as it try sot  

> maintain the 600 lbs. in the system prior to the start of an  

> engine.  At that time, the engine driven pump produces around 1000  

> lbs.  If the engine is running and the gauge only shows 600 then it  

> indicates a major loss of hydraulic fluid or both pumps are not  

> working.

>

> It the flap lever is not in the totally off position then I have  

> had the same symptoms that you are having.  Sometimes it is  

> difficult to feel the total off position of the flap handle as the  

> detent is not that noticeable.

>

> I am sure others with many more years of experience will chime in  

> an we will all learn from it.

>

> Don

>

> --

John Vormbaum

Joined: 21 Aug 2006
Posts: 273
Location: SF Bay Area, CA

Posted: Sat Apr 05, 2008 7:41 pm Post subject: Electric fuel pump cycling

Gary,

Tylor's input has merit, and Don is on the right track. The noise you 

hear is your aux hyd. pump running. You probably don't have a hose or 

line problem (unless you're losing hyd. fluid) because you're 

making/maintaining the correct 1,000 psi with the engine-driven pumps 

and ~5-600 psi with the aux pump....and you didn't mention any red 

racing stripes on the outside of the airplane in your original post.  

What you have is an excessively bypassing valve in your hyd. system. My 

memory is not clear enough to know if there is a way to determine if 

it's a flap or steering actuator (does putting the flap handle in 

neutral completely isolate the flap system from the hyd. pumps?), but 

you DO have a valve that is bypassing.

This has happened to me in my 500B on occasion, the last was a few years 

ago and it seemed to heal by itself.....I must have hit a big bump in a 

taxiway that freed up the offending valve .

Tylor's comments about pulling the aux pump breaker after takeoff are on 

the money. The hydraulic reservoir has a standpipe in it that limits the 

amount of fluid available to the engine-driven pumps. Theoretically, in 

the event of a hydraulic leak, with the aux pump off you will have fluid 

left in the reservoir for brakes on landing (remember to push the 

breaker in on final).

If you fail to pull the breaker after takeoff, and have a major leak, 

once the standpipe level is reached, the aux pump will happily continue 

to pump your valuable fluid overboard until the reservoir is dry. Ask me 

how I know. Even a slow, gentle nosegear collapse can get pricey....

/John

Tylor Hall wrote:

[quote] 

 <tylor.hall(at)sbcglobal.net>

 Gary,

 You want to hear the hydraulic pump and see 600 psi on the gauge 

 before you start the engines.  If the engine starts and you have no 

 pressure, it will roll forward unit the engine driven pump can pump up 

 enough pressure to make the breaks work.  Rolling forward when you do 

 not want to can be a problem of running into something.

 In the older 560/680, there is a hand pump that needs to be pumped up 

 to set the breaks.

 Are you aware that you can pull the circuit breaker on the electric 

 hydraulic pump after you take off?

 If you have a hose failure in flight, the electric pump will attempt 

 to keep the pressure up and pump all the hydraulic oil through the 

 broken hose?  There is a reserve amount in the hydraulic tank that 

 would allow you to stop the aircraft is you land and push in the 

 circuit breaker to make the breaks work.  It would be a no flap landing.

 When was the last time you inspected all the hydraulic hoses?  It is a 

 problem of aging aircraft.

 Just a thought.

 Tylor Hall

 On Apr 5, 2008, at 8:25 PM, Gary Giesler wrote:

> 

> <gjgiesler(at)hotmail.com>

> Don.

>        When the engines are driving their pumps the psi is around 

> 1000. And the needle is not twitching , I cant tell if the clicking 

> relay sound is there or not because of the noise. I will experiment 

> with finding the flap " OFF" detent......didn't know there was one.

>                                                                 Thanks

>                                                                             

> Gary      500RX

> ________________________________

>> From: dfalik(at)sbcglobal.net

>> To: commander-list(at)matronics.com

>> Subject: RE: Electric fuel pump cycling

>> Date: Sat, 5 Apr 2008 16:51:19 -0400

>>

>>

>> Gary,

>>

>>

>>

>> I am certainly no expert, but I have owned a 500S for 3 ½ years.  It 

>> is the electric hydraulic pump that you hear as it try sot maintain 

>> the 600 lbs. in the system prior to the start of an engine.  At that 

>> time, the engine driven pump produces around 1000 lbs.  If the 

>> engine is running and the gauge only shows 600 then it indicates a 

>> major loss of hydraulic fluid or both pumps are not working.

>>

>>

>>

>> It the flap lever is not in the totally off position then I have had 

>> the same symptoms that you are having.  Sometimes it is difficult to 

>> feel the total off position of the flap handle as the detent is not 

>> that noticeable.

>>

>>

>>

>> I am sure others with many more years of experience will chime in an 

>> we will all learn from it.

>>

>>

>>

>> Don

>>

>>

>>

>> --

cloudcraft(at)aol.com
Guest

Posted: Sat Apr 05, 2008 7:48 pm Post subject: Electric fuel pump cycling

My free opinion -- and worth every penny -- is that if your flap handle is in the neutral detent and your aux hydraulic pump is cycling quickly you should (in order of expense):

 

 Check the nitrogen charge on the hydraulic accumulator.  If just 50 psi low, it will cause cycling.  The hydraulic accumulator is high up in the left nacelle and has a Schraeder valve on it.  When you taxi or operate the flaps, do you have a hydraulic "slam?"  If so, that's also a symptom of low accumulator pressure.

 

 

    High pressure out-put from the engine hydraulic pumps is routed to a pressure regulator.  This pressure regulator is commonly called the accumulator XE "accumulator:hydraulic" \i <![endif]--><![endif]--> by pilots.  You should know that it is an accumulator, as well as a â€œloading & unloading valveâ€ that keeps hydraulic system pressure even and dampens pressure surges while operating any of the hydraulically actuated components.

   An important operating tip; when is the hydraulic accumulator low?    

    XE "nitrogen charge:hydraulic accumulator" \i <![endif]--><![endif]-->If you feel or hear a â€œslamâ€ during steering the Aero Commander on the ground, the nitrogen charge in this accumulator has dropped below the 600 psi required for normal system operation.  

 

 

  If a few dollars' squirt of nitrogen doesn't stop the cycling, the seals in the flap & landing gear control valve assembly need to be replaced.  That really means overhaul it.   That control valve assembly is under the center pedestal, floor.

 

 By the way, Tylor is correct about the electric aux hydraulic c/b.Wing Commander Gordon

 

   

 

  Life is not simple anywhere. Probably less so elsewhere.

   

 

   

 

 --

John Vormbaum

Joined: 21 Aug 2006
Posts: 273
Location: SF Bay Area, CA

Posted: Sat Apr 05, 2008 8:46 pm Post subject: Electric fuel pump cycling

Keith, nice! I forgot all about the accumulator....



/John



Keith S. Gordon wrote:

[quote] *My free opinion -- and worth every penny -- is that if your flap 

 handle is in the neutral detent and your aux hydraulic pump is cycling 

 quickly you should (in order of expense):



 Check the nitrogen charge on the hydraulic accumulator.  If just 50 

 psi low, it will cause cycling.  The hydraulic accumulator is high up 

 in the left nacelle and has a Schraeder valve on it.  When you taxi or 

 operate the flaps, do you have a hydraulic "slam?"  If so, that's also 

 a symptom of low accumulator pressure.

 *

 High pressure out-put from the engine hydraulic pumps is routed to a 

 pressure regulator.  This pressure regulator is commonly called the 

 accumulator by pilots.  You should know that it is an accumulator, as 

 well as a â€œloading & unloading valveâ€ that keeps hydraulic system 

 pressure even and dampens pressure surges while operating any of the 

 hydraulically actuated components.

     An important operating tip; when is the hydraulic accumulator low?



  

 If you feel or hear a â€œslamâ€ during steering the Aero Commander on the 

 ground, the nitrogen charge in this accumulator has dropped below the 

 600 psi required for normal system operation. 



 *

 If a few dollars' squirt of nitrogen doesn't stop the cycling, the 

 seals in the flap & landing gear control valve assembly need to be 

 replaced.  That really means overhaul it.   That control valve 

 assembly is under the center pedestal, floor.



 By the way, Tylor is correct about the electric aux hydraulic c/b.

 **

 Wing Commander Gordon

 *



 Life is not simple anywhere. Probably less so elsewhere.

 --

bobf(at)feldtman.com
Guest

Posted: Sun Apr 06, 2008 9:05 am Post subject: Electric fuel pump cycling

I know this is an entirely dirrent string. but--

  

 the commander is wonderful it has three hydraulic pumps one elec and two engine. if all three fail and or the fluid pumps out (shouldn't if you follow directions as noted wrt cir brker)

  

 then you CAN get all the gear down - first with the N2 blow down bottle assuming it is topped off. if it is too low, just slow down to right above stall, pop the nose up and the gravity will pull down the gear as you put the gear handle down. the bungee cords on the mainlys will lock them over TDC and they will latch.. and the nose should lock too. three green will confirm it. a nicely pollished spinner on the props will allow you to look at the nose gear to see it is down. So I don't plan to have a nose gear collapse in my 500B!

   

 Now - reverse steering with a blown o ring in the nose gear steering is another topic!

  

 bobf

  

 500B



 

 On 4/5/08, dfalik(at)sbcglobal.net (dfalik(at)sbcglobal.net) <dfalik(at)sbcglobal.net (dfalik(at)sbcglobal.net)> wrote: [quote]   

Gary,  

  

I am certainly no expert, but I have owned a 500S for 3 ½ years.  It is the electric hydraulic pump that you hear as it try sot maintain the 600 lbs. in the system prior to the start of an engine.  At that time, the engine driven pump produces around 1000 lbs.  If the engine is running and the gauge only shows 600 then it indicates a major loss of hydraulic fluid or both pumps are not working.  

  

It the flap lever is not in the totally off position then I have had the same symptoms that you are having.  Sometimes it is difficult to feel the total off position of the flap handle as the detent is not that noticeable.  

  

I am sure others with many more years of experience will chime in an we will all learn from it.  

  

Don 

  

--

dfalik(at)sbcglobal.net
Guest

Posted: Sun Apr 06, 2008 11:06 am Post subject: Electric fuel pump cycling

All,



Just to share:



In the last year, I have had two occasions of loss of all hyd.

Pressure/fluid due to holes in the hydraulic lines.  Each time I was

airborne and the landing and roll out was no issue due to the remaining

fluid in the reservoir and the electric hyd. Pump.  I would be real

hesitant to pull the breaker after take off and then have another thing

to remember before landing.  With the catastrophic loss of fluid the

landings again were a non issue.  The first time the line was in the

baggage area with the unpleasant result obvious.  The second time it was

fitting between two sections of line but this time it was in a wing root

with the fluid running down the side of the fuselage.



Recently, within the last 3 months, I had another issue where after

start up the hydraulic pressure didn't register above 600 and I assumed

it was failure of the engine driven pumps (again).  It turned out to be

the accumulator/regulator.  Apparently something in the regulator wears

and needs to be overhauled.  There is only one place in the country that

does it and the overhauled part is sold through commander service

centers.  It is a $4900.00 item with a $4000.00 core charge to assure

them that your part is able to be overhauled.  Replacing the part solved

the problem and luckily my core charge was returned to me a month or so

later.



Again, this is just to share experiences and I am always open to other

more knowledgeable comments.



Don



--

rcdettmer(at)charter.net
Guest

Posted: Sun Apr 06, 2008 11:25 am Post subject: Electric fuel pump cycling

Thanks for the excellent discussion regarding hydraulic systems.  That's

what makes this forum so valuable and helpful to Commander owners.  I am

getting all new hydraulic hoses with the new engines in my 680F.  I have

added the "pull the hydraulic pump switch" to my climb-out check list, and

of course try to remember to push it back in prior to landing.  Thanks again

for the great comments.



Randy Dettmer, AIA

680F/N6253X



Dettmer Architecture

663 Hill Street

San Luis Obispo, CA  93405

805 541 4864 / Fax 805 541 4865

www.dettmerarchitecture.com



--

nico(at)cybersuperstore.c
Guest

Posted: Sun Apr 06, 2008 3:01 pm Post subject: Electric fuel pump cycling

I wrote earlier about a total hydraulic loss in my straight 500 a  number of years ago and slowing down to just above stall-speed popped the gear  down and locked without any hesitation. After an uneventful landing (I believe I  feathered both engines on short final just in case), without hydraulics, the  plane stayed on the center line and as it slowed down it slowly castered off the  runway into the rough where it came to a halt. The fire truck picked me up and I  had the FBO tow it back to the shop. It wasn't a non-event but the in-flight  hydraulic failure was more of a heart-stopper than the  landing.

  



   From: owner-commander-list-server(at)matronics.com  [mailto:owner-commander-list-server(at)matronics.com] On Behalf Of Robert  Feldtman

Sent: Sunday, April 06, 2008 10:03 AM

To:  commander-list(at)matronics.com

Subject: Re: Electric  fuel pump cycling

 

 I know this is an entirely dirrent string. but--

  

 the commander is wonderful it has three hydraulic pumps one elec and two  engine. if all three fail and or the fluid pumps out (shouldn't if you follow  directions as noted wrt cir brker)

  

 then you CAN get all the gear down - first with the N2 blow down bottle  assuming it is topped off. if it is too low, just slow down to right above  stall, pop the nose up and the gravity will pull down the gear as you put the  gear handle down. the bungee cords on the mainlys will lock them over TDC and  they will latch.. and the nose should lock too. three green will confirm it. a  nicely pollished spinner on the props will allow you to look at the nose gear to  see it is down. So I don't plan to have a nose gear collapse in my 500B!

  

 Now - reverse steering with a blown o ring in the nose gear steering is  another topic!

  

 bobf

  

 500B



 

 On 4/5/08, dfalik(at)sbcglobal.net (dfalik(at)sbcglobal.net) <dfalik(at)sbcglobal.net (dfalik(at)sbcglobal.net)> wrote:   	  Quote: 	
		           

Gary,   

    

I am certainly no    expert, but I have owned a 500S for 3 ½ years.  It is the    electric hydraulic pump that you hear as it try sot maintain the 600 lbs. in    the system prior to the start of an engine.  At that time,    the engine driven pump produces around 1000 lbs.  If the    engine is running and the gauge only shows 600 then it indicates a major loss    of hydraulic fluid or both pumps are not working.   

    

It the flap lever is    not in the totally off position then I have had the same symptoms that you are    having.  Sometimes it is difficult to feel the total off    position of the flap handle as the detent is not that    noticeable.   

    

I am sure others with    many more years of experience will chime in an we will all learn    from it.   

    

Don   

    

-----Original    Message-----

From: owner-commander-list-server(at)matronics.com (owner-commander-list-server(at)matronics.com) [mailto:owner-commander-list-server(at)matronics.com (owner-commander-list-server(at)matronics.com)] On Behalf Of Gary Giesler

Sent: Saturday, April 05, 2008 11:13    AM

To: commander-list(at)matronics.com (commander-list(at)matronics.com)

Subject: Electric fuel    pump cycling   

    

  Question

 

     Before starting the engines i am hearing a pulsing relay clicking that    continues even after the flaps are retracted.The hydraulic pressure needle is    twitching around 600psi as it makes this noise. If I step on the brakes the    pump will work continuous untill just short of redline. After the brakes are    released the pressure drops back to six hundred and the clicking relay    sound comes back. Have I just never noticed this untill now, I have owned    500RX for a year, or is this a problem    ?

 

                                                                                                               Gary

                                                                                                             500RX--1974    500S         

   

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dfalik(at)sbcglobal.net
Guest

Posted: Mon Apr 07, 2008 7:17 pm Post subject: Electric fuel pump cycling

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