Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Solenoids. What Are They For In Fuel Sys. Of B76?  
User currently offlinelevashov From Russia, joined Aug 2010, 12 posts, RR: 0
Posted (3 years 6 months 1 week 15 hours ago) and read 4050 times:

Hello!

I've just started my multy commercial training with Beechcraft 76 Duchess. While im going thru the fuel system i found on the system schematic that in the priming pipe between auxiliary pump and primer there is an "primer solenoid", as well as in pipe going to the heater is "heater solenoid".

In the system description of engine priming: The battery master and the aux fuel pump (l or R) switches must be turned on prior to activating the fuel priming system. The push to prime switch may be actuated in either the both or start position. Pushing in on the magneto/start switch activates a solenoid, located behind the firewall in each nacelle, and supplies fuel directly into the no. 1 2 and 4 cylinders for engine priming.

The questions are:

What are those solenoids for? My instructor said that the main purpose of solenoids is to drive the fuel from the tank into the cylinders (or to heater in cabin heating system). But im quite unsure with his answer, because it seems to me not logical. My guess is that that solenoids is like a shutoff valve. They are not driving fuel itself (it must be done by pump), but opening valve in pipe so fuel can go to cylinders when priming activated, or heater system switched on.

Could you, guys, who familiar with what are solenoids, what are they for in fuel system for, explain me this. And if you have pictures or schematics of how that kind of solenoids looks like to share a link.

Thank you very much!

4 replies: All unread, jump to last
 
User currently offlineWingscrubber From UK - England, joined Sep 2001, 854 posts, RR: 0
Reply 1, posted (3 years 6 months 1 week 12 hours ago) and read 4017 times:

I'm not intimately familiar with the Duchess fuel system, but you are correct in presuming that 'solenoid' in fuel or hydraulic systems usually infers 'solenoid actuated shut-off valve'.

I'm only a PPL, but 'priming' the engine prior to start on the 172 is a matter of switching on the fuel pump to pressurize the system, then opening the mixture to allow some fuel to flow before closing it again, and then turning the pump back off.

On the Duchess, seems as though you activate the pump to pressurize the system, and then either with the priming switch or mag switch, the solenoid opens and allows fuel to flow into the intake manifold of the engine before you start?

Also, if the engines are fuel injected, or maybe if fuel is not gravity fed, then a fuel pump must run continuously to deliver fuel to the engine. I think sometimes this might be mechanically driven on old airplanes...

http://en.wikipedia.org/wiki/Solenoid_valve
http://ma3naido.blogspot.com/2007/10...raft-fuel-systems-fuel-primer.html

Hope that helps...?



Resident TechOps Troll
User currently offlinelevashov From Russia, joined Aug 2010, 12 posts, RR: 0
Reply 2, posted (3 years 6 months 1 week 11 hours ago) and read 4012 times:

Oh yes, thank you very much. That what i was looking for!

User currently offlinezeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 3, posted (3 years 6 months 1 week 8 hours ago) and read 3970 times:

Quoting Wingscrubber (Reply 1):

On the Duchess, seems as though you activate the pump to pressurize the system, and then either with the priming switch or mag switch, the solenoid opens and allows fuel to flow into the intake manifold of the engine before you start?

I think on the dutches the prime line is downstream of the aux fuel pump. Pushing the mag switches in opens the solenoid valve with fuel under pressure from the aux pump directly to the primer nipples into 3 cylinders.
Been a while since I have flown one, could be wrong.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 4, posted (3 years 6 months 6 days 13 hours ago) and read 3809 times:

You can think of solenoids as large electrical relays, which usually provide some sort of mechanical movement.

Solenoids are often used to actuate valves. They are on/off normally.

The Piper Seminole has a similar system. The priming system uses solenoids as well IIRC

Quoting levashov (Reply 2):
Oh yes, thank you very much. That what i was looking for!

Google has all the answers   


Top Of Page
Forum Index

Reply To This Topic Solenoids. What Are They For In Fuel Sys. Of B76?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
What Are These Openings On The Belly Of The 757 posted Wed Mar 10 2010 09:27:35 by c5load
What Are The Small Bars On Top Of Doors? posted Tue Apr 18 2006 14:45:08 by Keta
What Are Winglets For? posted Wed Apr 5 2006 07:59:35 by Okees
Startup Airline Costs. What Are They? posted Wed Nov 16 2005 12:12:22 by ZKSUJ
Bleedless Engines... What Are They? posted Mon Oct 31 2005 17:49:17 by D L X
What To Look For In Good CFI Training? posted Mon Oct 21 2002 20:09:54 by DG_pilot
C Check D Check What Are They (novice) posted Mon May 20 2002 20:13:09 by BWIA 772
What Are The Rules For Record Locators? posted Tue Mar 29 2011 17:03:11 by Hagic
What Are Commonly Replaced Sesors For CRJ Aircraft posted Mon Aug 9 2010 10:32:26 by ToddH
We Are Looking For Aviation Lawyer In UK posted Wed Jun 2 2010 15:33:29 by aabinitio

Sponsor Message:
Printer friendly format