sseeker Posted February 27, 2011 Posted February 27, 2011 Hi, While I can't find anything in the manual about this, would it be appropriate to use the electric pump when landing? Being a Jabiru+Gazelle pilot I've always been taught to switch the backup pumps on on downwind, both of these aircraft are high wings so they obviously have some gravity behind them. I was told not to use the backup pump in the SportStar on downwind as it was only to aid in starting. While this seems accurate (the sporty is low wing) should I use it? Does it have enough power behind it to keep the engine running if the mechanical pump quits? Most other low wing aircraft I've been in have a fuel pump and an electric boost pump however the SportStar just has the 1 extra electric pump... -Andrew
dazza 38 Posted February 28, 2011 Posted February 28, 2011 Generaly in all the low wing A/c i have flown. Fuel pump is turned of as apart of my downwind checks.Having said that, maybe the sportstar is different. Its interesting that you cant find it in the POH.I have never flown a sporstar, Bass, and your instructor will know .Also you could PM Peter Harlow the Aus Importer he is a member here.I just cant off the top of my head think of his User name.
Mick Posted February 28, 2011 Posted February 28, 2011 For what it is worth, in our Sportstar we used the three "C's" to determine when the electric fuel pump was used - Climb - pump on Circuit- pump on Cruise- pump off The Sportstar being Rotax powered the engine has a mechanical fuel pump built onto it. The electric "boost pump" is there to take on the job if the mechanical one fails. An essential item in a low wing where you won't get fuel gravity feeding if a pump fails.
sseeker Posted February 28, 2011 Author Posted February 28, 2011 Yes I thought this was the case although my CFI says the boost pump can't provide enough pressure to keep the engine running if the mechanical pump quits... Regards, Andrew
turboplanner Posted February 28, 2011 Posted February 28, 2011 My checklist for both Jabiru and Cherokee is: Pre-Takeoff at the holding/runup point: Fuel pump on Turning Crosswind: fuel pump off Downwind checks: fuel pump on In GA flying the reason for this is automatic redundancy; on short final, or a go round you don't have to stop and think; if the mechanical fuel p;ump at those points fails the electric pump takes over. It's hard to understand why a Recreational Aircraft manufacturer would design a backup system which doesn't have full redundancy, it would miss the point.
facthunter Posted February 28, 2011 Posted February 28, 2011 The fuel tank pump has another purpose. To ensure there isn't any vapourlocking. With Mogas this is more likely than with avgas. Are we certain that the elec pump won't bypass the engine pump, in event of it failing? IF the valves are lightly loaded it will flow through it. Checking this is easy , Juat disconnect a hose downstream of the engine pump and check if any flow, with elec fuel pump ON. Nev
winsor68 Posted March 1, 2011 Posted March 1, 2011 My training has been electric pump on as part of pre-landing checks... and remains on for takeoff/go around until cross wind turn... to me it just makes sense from a safety perspective. I have had the impression that this is just standard practice... but perhaps not with all high wing aircraft... I can't help thinking of my dear Uncle Doug when I flip the switch... perhaps reading this will help- like turning the fuel pump on it certainly can't do any harm... http://www.atsb.gov.au/publications/investigation_reports/2000/aair/aair200000885.aspx
facthunter Posted March 1, 2011 Posted March 1, 2011 That is sad and a pretty convincing argument. Lots of high wing aircraft do not have fuel pumps fitted as they have a "height of fuel" that is considered enough to ensure an adequate fuel flow rate. I would suggest turning pumps on prior to take-off and turn them off at a SAFE height. Also entering the circuit till after landing. Its a shame when a perfectly operable aircraft suffers from fuel starvaton.. As you say "it can't do any harm". You should check fuel pressures to ensure that the pressure is in the correct range. High fuel pressure can cause carburetter flooding and possible fire. Nev
ahlocks Posted March 1, 2011 Posted March 1, 2011 A backup electric fuel pump was/is an optional item, which is probably why it is not included in the standard checklists. It is referred to in the prestart checklist in the POH and in the Evektor LSA training manual though. For what it's worth, I run the pump at pre start to confirm its operation and to prime and pressurise the fuel system then shut it off again before starting. The Electric fuel pump is switched back on; Pre take off until ~700ft agl As part of engine out drills and PFL practice During pre landing checks until end of roll out.
Ryanm Posted March 1, 2011 Posted March 1, 2011 Yes I thought this was the case although my CFI says the boost pump can't provide enough pressure to keep the engine running if the mechanical pump quits...Regards, Andrew Worked for me when the mechanical pump failed. We had the pump on basically any time you were below 1000ft, as well as when changing tanks in the cruise.
Bryon Posted March 1, 2011 Posted March 1, 2011 I was taught - all switches up at the holding point (this included the fuel pump) on takeoff and on downwind my checks were BUMPFFH Brakes Undercarriage Mixture Pump Fuel - switch on and Fuel sufficient Hatches and harnesses secure This is a check that I run through on downwind regardless of the aircraft I am flying To me, the pump should be on on takeoff and landing as they are the most critical parts of flight and if I can lessen the risks, I will do it Bryon
turboplanner Posted March 2, 2011 Posted March 2, 2011 In GA, mine is BOUMFH In RAA, we could use a checklist B Brakes operating (hyd backpressure) and off O Oil temp and pressure normal U Undercarriage down M Mixture rich, master on, mags to both F Fuel on, fuel pump on, fuel sufficient for exercise H Hatches, Harnesses secure I'm with you Bryon, if you're going to memorise something best not to change it - I did a few flights in a retractable
dazza 38 Posted March 2, 2011 Posted March 2, 2011 I use bumpfish as well.It depends on where people are trained.
winsor68 Posted March 2, 2011 Posted March 2, 2011 Bufhel for me... Brakes-Off Undercarriage- Still there Fuel- Enough and pump on Harness/hatches-Check Engine- Scan gauges Look out
kgwilson Posted March 2, 2011 Posted March 2, 2011 Pre startup check - Pump on Startup - Pump Off Pre takeoff checks - Pump on Climb out/crosswind - Pump Off Changing tanks - Pump on Downwind Checks - Pump on Exit to taxiway - pump off This from the Piper Cherokee Archer manual now safely packed away for my move south. I am not sure if it is Mr Piper or Mr Lycoming who is responsible but it makes good sense. Bumf, Bumph, Bumfish, Boumf, Bumpffh or any other 4+ acronym doesn't matter so long as it pertains to the aircraft you are flying and it makes you remember all those things to check.
sseeker Posted March 2, 2011 Author Posted March 2, 2011 Thanks for all the replies, I personally use BUMFHI. Brake pressure sufficient & park brake off, Undercarriage is down, Mixture is full rich (irrelevant to most raa planes), fuel is sufficient + pump on, hatches & harness' secure & ignitions set both. On my first flight in the sporty I turned the pump on as apart of my checks (as I usually do) although the instructor said it wasn't necessary, it wasn't a bad habit either. I've flown in other low wings and it's always required that the pump is turned on during downwind, changing tanks, takeoff etc... The SportStar Plus POH doesn't state that the pump should be on. -Andrew
rdarby Posted March 2, 2011 Posted March 2, 2011 Why do you put it on when changing tanks in the cruise? I was taught to do as you all mention above but that one is new to me, but then again I'm only starting to really understand the fuel system now too.
facthunter Posted March 3, 2011 Posted March 3, 2011 To avoid an airlock. The engine pump will not function well if it gets air into it. It's a back-up. Nev
Ryanm Posted March 3, 2011 Posted March 3, 2011 As facthunter said, just to ensure there is no airlock. Its in the manuals for most aircraft to do this (PA31, C402 etc)
SilverWing Posted April 6, 2011 Posted April 6, 2011 A belated comment on the SportStar back-up electric fuel pump - my computer has been blocking entry to the RecFlying site for some reason. The SportStar Pilot Manual states: Electric fuel pump operates during engine starting period only. It is not intended for long continuous operation for long time. In a separate section it also indicates the pump should be used for start up and switched off after take-off. It should be switched on as part of downwind checks and off after landing. It should also be switched on if there is a no-fire in flight engine stop. And switched off before any emergency landing. Hope this is helpful.
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