Simultaneous Engine starts?

[Guest stevesj]

Hi JonJust back to the DVD for a mo. Alan C says " this aircraft has an excellent apu and enables us to start two engines at once, which we are doing now with engines 1 & 2". As 4 & 3 are already running are they not creating enough duct air pressure with or without the (excellent) APU ?CheersSteve ps as a matter of interest are they all still with VS on 744's ?

[dude6595 0]

Air France cargo was at SAT one day, i use to work there, dont know what the heck they were doing there but anyways, when they left they started 3 and 4 and then 1 and 2. was cool, first time seeing a 744F.

[jon b 2,047]

Hi Steve,Got your mail,yes I got distracted by a real flight you were right!In answer to your question,yes you could easily do a cross bleed start with 2 engines going,with only 1 engine you need to use about 70% N2 to get enough pressure.Standard procedures though use the APU to start all 4 using the APU bleed.Alan C has left,Alan R is still around,busy selling cars as a side line! and the other fellow has been on sick leave for years with a bad back(allegedly last seen water skiing in capetown!)regardsJon

[Ralgh 43]

During walkarounds at LAX I watch the guys come off the international termianl. I have seen the one at a time and the 3&4 then 1&2. United starts then 4, 1, 2, 3. My buddy tells me that is because the brakes are on the 4 hydraulics. My question is why is that such a big deal? If I understood the manual correctly the demand pump should provide enough pressure and the 1 & 2 should back it up. And isn't there an accumulator too? Of course I am well aware a fleet program managers whim can make a big difference. We have 737-800s 757/767s and 777 that all have some similar if not identicle systems and we seem to have differnt procedures for each plane.

[Guest 744nut]

"because the brakes are on the 4 hydraulics"If you put HYDR #4 demand on AUX there is enough presure for the brakesTon

[Guest The_Glideslope]

WARNING: This might sound Stupid!On the real manual of the 767 (i know it's a diferent system from the 744) Boeing is quite touchy when it concerns engine hours Vs. startup procedures.There's this procedure that we should use Starter 1 for odd days and Starter 2 for even days. Furthermore, Engine 1 should be started first on even days and Engine 2 first on odd days (it might be the other way around, I don't have the manual with me right now).I read here pilots starting Engine 4 first almost all the times on the 744. How does that interfere with Engine hours and does the real manual have this rather strict code for start up like the 767?I warned you it sounded stupid...

[Guest boxjockey99]

JohnAre you sure this doesn't relate to ignitor systems? I've heard no such rule on the 757 or 737 but it is recommended to change the ignotors over every sector. This is particularly important in the 737 when we always did the first sector on the Left Ignitor to ensure we could restart from the standby power system in the event of a double engine flame out. This is a no go item and far better find out about it when still at home base and not somewhere down route. It is inevitable that engines will accrue more hours when on the right wing as they are invariably started first but most operators build this in to the maintenance and swap engines round to ensure an even spread of hours although the 90 seconds or so of difference really will not make a thunderous difference over 2500hr standard time between maintenance for the average jet engine. Kris

[Guest The_Glideslope]

Normal Procedures Checklist Boeing 767-200Cockpit Preparation(...)Ignition Switch.............................................SetSet 1 for ODD days, 2 for EVEN days, BOTH for Cold Weather Ops.(...)This is it. Perhaps it got it wrong, since on the same procedures the Engines state "Recomendation: Number 2 Engine First, Except per Airline specification"Is this present in real 744 procedures?

[markadeane 272]

Hopefully Allan R has picked up a 4th stripe? He seemed to be good left-seat material judging by his FO abilites, very thorough and proactive.

[Ralgh 43]

The only reason I question that logic is because system 1 will provide alternate braking as well as system 2. Demand pumps 1-3 should be in AUTO providing pressure for those systems and 4 should be in AUX providing pressure for 4. There should be adequate pressure for the brakes no matter which engine is started first. Or else I have the system wrong which considering its me that is entirely possible.In the 737 we taxi on engine 1 all the time. Brakes are on the B system which is on engine 2. We still have the electric pump for system B which is less powerfull than the demand pumps on the 747 and alternate brakes on the A system.

[Qavion 19]

"If I understood the manual correctly the demand pump should provide enough pressure and the 1 & 2 should back it up. And isn't there an accumulator too?"The demand pump on the #4 Hydraulic system is an air-driven pump. It does use up a lot of air which could be used to start an engine or two.Of course, you are right about the redunancy of the braking system.... but why not always do the safest thing you can do ;) One could also suggest you switch off 3 engines during descent to save fuel :(Cheers.Q>

[Chaos81 110]

>The demand pump on the #4 Hydraulic system is an air-driven>pump.I never knew that. Although, there are quite a few things I don't know about the 747. ;)I always love reading your posts and the information you give out. Sometimes I wish you would just post random things you know, that most of us wouldn't.:-lol

[cowpatz 243]

It quite often depends as to whether or not auto start is used as well. In our fleet we have a combination of GE and RR powered aircraft. The GE's are equipped with autostart and we start 3 & 4 and then 1 & 2. On the RR we do not have autostart and we start 4,1,2,3 one at a time. It would be possible to start 2 engs manually on the RR ones but it comes down to adequate monitoring for potential start faults.I guess different airlines have different start procedures.CheersSteve

[Qavion 19]

"On the RR we do not have autostart and we start 4,1,2,3 one at a time."Interesting... I don't think I've seen a Roller-powered 744 without Autostart. P&W took a while before they developed an Autostart system... and for some reason, they produced a system with 4 Autostart switches.Regards.Q>

[Guest]

>Air France cargo was at SAT one day, i use to work there,>dont know what the heck they were doing there but anyways,>when they left they started 3 and 4 and then 1 and 2. was>cool, first time seeing a 744F.you were lucky, you got to see an 747-400ERF! Not many of those around