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Engine # Start  
User currently offlineRadarcontact From , joined Dec 1969, posts, RR:
Posted (9 years 4 months 3 days 10 hours ago) and read 2589 times:

Hi all,

I've been on several twin-engined flights, B737, B767, B757, B777, A320, DASH8, ATR72, Piper 34 and so on. What I still don't understand is that always engine # 2 is started up first. I've even asked this to a KLM B737 captain during a cockpit flight, but he couldn't answer this question.

I've come up with an idea which might be completely wrong, but it goes like this: Since passengers are boarded via the left side of airplanes, engine # 1 is started up as last for a possible safety reason. Am I correct?

Any ideas/suggestions?

19 replies: All unread, jump to last
 
User currently offlineMiamiair From , joined Dec 1969, posts, RR:
Reply 1, posted (9 years 4 months 3 days 10 hours ago) and read 2560 times:

That used to be the logic behind it.
.
.
.


User currently offlineStaffan From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 4 months 3 days 10 hours ago) and read 2556 times:

Not 100% sure, but I recall it having to do with which engine that drives the pump supplying pressure to the parking brake. I could be wrong though.

Staffan


User currently offlineVenus6971 From United States of America, joined Dec 2004, 1438 posts, RR: 1
Reply 3, posted (9 years 4 months 3 days 10 hours ago) and read 2540 times:

Which ever engine that will supply hydraulic pump pressure as soon as possible.


I would help you but it is not in the contract
User currently offlineMiamiair From , joined Dec 1969, posts, RR:
Reply 4, posted (9 years 4 months 3 days 10 hours ago) and read 2522 times:

Not necessarily true. The brake has pressure in an accumulator. And there are electric pumps also. On the old jets it was #4, #3, #1 and #2, as the L/H side was the "exit."

When in doubt, follow the directions, read the manual.


User currently offlineJetMechMD80 From United States of America, joined Jul 2004, 380 posts, RR: 7
Reply 5, posted (9 years 4 months 3 days 1 hour ago) and read 2363 times:

I have to agree with Miamiair. Another reason also, we don't start engines at the gate unless we have an APU on MEL. We normaly start them during the push back. But if we do need a huffer, the unit is normaly parked on the left side. You wouldn't want to start the left engine, and take a chance of sucking the huffer hose into the inlet. But I still agree with Miamiair, its because the jetbridge is on the left.


"I get along great with nobody"~ Billy Idol
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 6, posted (9 years 4 months 2 days 23 hours ago) and read 2357 times:

I've come up with an idea which might be completely wrong, but it goes like this: Since passengers are boarded via the left side of airplanes, engine # 1 is started up as last for a possible safety reason. Am I correct?

Since the RH side is used for Servicing [Gallery,Cargo,Water,Toilet],Which is normally completed well before Startup.Hence by starting #2 first to save time,Last minute activity thru the Fwd Entry door can be accomplised safely.

On the old jets it was #4, #3, #1 and #2, as the L/H side was the "exit."

On Four Engined jets is the above sequence correct,Should there not be a stagger to avoid a pull on one wing.I would think #4,#1,#3,#2,can anyone confirm.
regds
MEL



Think of the brighter side!
User currently offlineMiamiair From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 4 months 2 days 19 hours ago) and read 2329 times:

The start sequence has nothing to do with the stress a power plane exerts on a wing, eccentric loading is not an issue as the design is based on a multitude of variables. And the 4312 was done so that the powerplant furthest from the fuselage was started first.

User currently offlineBR715-A1-30 From , joined Dec 1969, posts, RR:
Reply 8, posted (9 years 4 months 2 days 12 hours ago) and read 2282 times:

I've only seen engines started with #1 first. I do know that some pilots on the 727, DC-10, MD-11, and L-1011, would start #2 at the gate right before pushback and taxi on that one and while taxiing would start 1 & 3. Saves time and fuel.

User currently offlineRadarcontact From , joined Dec 1969, posts, RR:
Reply 9, posted (9 years 4 months 2 days 11 hours ago) and read 2259 times:

At AMS most aircraft startup during pushback. I think that's more save than starting up while still at the gate.

Does it technically seen matter which engine is started up first with an active APU? Or is there always one specific engine which is equipped with a hydraulic pump?


User currently offlineFadec From United States of America, joined Jun 2004, 45 posts, RR: 0
Reply 10, posted (9 years 4 months 2 days 9 hours ago) and read 2235 times:

We would start #2 first to insure there is no hydraulic power being supplied to the steering actuators. This is primarily a safety measure should you either forget to install the steering hydraulic bypass pin on the nose gear or if the bypass failed. On Boeings the normal breaks are run off the right system, the steering is off the left. Whether the right be the #2 or #4 for the 747. 727's and 737's "B" is on the #2 engine with no #3 hyd system installed. On the DC-10 systems #1 and #3 run the breaks and steering at equally, so #2 is started first.

This was an old throw back from the days of the 737-200's which does not have a steering bypass valve. Should they accidentally leave the hydraulic interconnect closed "B" system would pressurize "A" system and nose gear would go strait, thus breaking the towbar. It is the same for the 727 with an interconnect, but there is hyd bypass installed for protection.

On normal pushbacks we would only turn on the right system electric hydraulic pump to insure we have breaks and leave the other electric pumps off until after engine start. Then we would not turn the #1 engine until the pushback driver disconnected from the aircraft and/or cleared us for #1 start. Once all was up and running then everything is turned on as normal. This procedure was followed no matter what we were driving. Whether it be an old or modern Boeing, Airbus, or Douglas. The 747 being the only odd ball, which requires the #1 hyd. system to be pressurized for main gear steering.

Once you get into the prop aircraft everything changes and I have no clue what order or reason they use.


User currently offlineTimT From United States of America, joined Jun 2001, 168 posts, RR: 0
Reply 11, posted (9 years 4 months 2 days 3 hours ago) and read 2189 times:

It used to be that the engine closest to the battery was started first, but now in the days of gas turbines using air for start that's not true. I have the most experience with the DC-10 and it really makes no difference in the order of start. BUT (there's always one of those, isn't there) many Pilots like to start #3 first because the ground crew, maintenance, push crew, etc., are usually standing on the left side to maintain visual contact with the Captain. And then to wave him off. Starting #3 first, the usual order is 3,1,2. I have learned that if the APU is a little funky, you can cheat a little and start #2 first because it has a little less air volume to recover from (shorter ducting).
The checklist I use turns on the electric hydraulic pumps and you have full pressure for brakes and steering right away.


User currently offlineSudden From Sweden, joined Jul 2001, 4130 posts, RR: 6
Reply 12, posted (9 years 4 months 1 day 21 hours ago) and read 2161 times:

Hi guys,

if I'm not mistaking, here in Europe they are not even allowed to make start up at gate. (Correct me if I'm wrong).
Only exeption is when using an airstarter, naturally.

I worked 4 years at GOT as loadmaster and no.2 was always started first.
It also has to do with where the batteries are placed. Shorter travel of power, means saving the batteries. Conclution is that the pilot would start the engine most close to the battery.
(Info gathered from a friend who is a cargopilot).

Aim for the sky!
Sudden



When in doubt, flat out!
User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4738 posts, RR: 26
Reply 13, posted (9 years 4 months 1 day 18 hours ago) and read 2149 times:
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WN starts the #2 engine first with the unusual exception that the ground crew is throwing very last minute bags in the bin in which case, to keep from interrupting the start-up/pushback procedure, they will start the #1 engine first. I believe this is rather new to the company. Until recently, the #1 engine was always started first. I can't remember the exact reason for the switch, but I swear I heard it has to do with systems hooked up and powered by the #2 engine. I should know, but I just can't think of it right now. I want to say cabin air, or A/C or something...


ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 14, posted (9 years 4 months 1 day 13 hours ago) and read 2109 times:

This was an old throw back from the days of the 737-200's which does not have a steering bypass valve. Should they accidentally leave the hydraulic interconnect closed "B" system would pressurize "A" system and nose gear would go strait, thus breaking the towbar
Not until the Parking Brake is set.
regds
MEL



Think of the brighter side!
User currently offlineAAR90 From United States of America, joined Jan 2000, 3451 posts, RR: 47
Reply 15, posted (9 years 4 months 1 day 13 hours ago) and read 2112 times:

I want to say cabin air, or A/C or something...

Correct. With right (#2) engine running the crew can isolate the right pneumatic system from the left system (and APU) permitting two A/C pack operation from two air sources [much more efficient maintaining cabin temp that way]. Boeing's recommended start sequence also simplifies single-engine taxi procedures as virtually all switch positions are ready for flight and the crew only needs to turn off the left A/C pack to start the left engine and turn it back on again for takeoff.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineFadec From United States of America, joined Jun 2004, 45 posts, RR: 0
Reply 16, posted (9 years 4 months 1 day 10 hours ago) and read 2083 times:

Not until the Parking Brake is set.

We have broken tow bars with both breaks set and not set. As long as hydraulic pressure is on "A" system and there is no input from the tiller the steering will go strait.


User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 17, posted (9 years 4 months 21 hours ago) and read 2035 times:

If System B Pumps are on + Grd Interconnect Open + Parking Brakes Selected,The A System is Pressurised.
If on Running Engines,System A Pumps selected,A System is pressurised.
The Switching off of A System Pumps only Energizes the A system Depressurising Solenoid,But a power loss can cause that solenoid to Deenergize & the Pumps to Generate pressure,Hence the Steering Disconnect valve is favoured & A pumps required to be selected off for pushback & no pushback with Engines running [ON B732s]
regds
MEL



Think of the brighter side!
User currently offlineRadarcontact From , joined Dec 1969, posts, RR:
Reply 18, posted (9 years 4 months 9 hours ago) and read 2012 times:

Allright, all of you thanks for reacting

Am I correct to conclude that engine nr 2 is started up first, because:

- It allows last minute actions on the left side of the aircraft
- The engine that should be started up first activates vital mechanisms such as the hydraulic system, airconditioning, cabin pressure, etc.
- It is more effective to startup the engine which makes the shortest connection to these vital mechanisms

Let me know if I missed anything

Merry X-mas!



User currently offline747Loadmaster From Germany, joined Oct 2004, 59 posts, RR: 0
Reply 19, posted (9 years 3 months 3 weeks 2 days 14 hours ago) and read 1848 times:

I think it is up to the company, the one I work for starts 1 2 3 4 .

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