Why start right engine first?

[Glonass]

I wonder why the engine start sequence is right first and then left. Is this the sequence you apply as well for you airplane? And why?

[PAXboy]

Aircraft are designed with passenger doors on the left. As these doors are still being closed and other personnel in the area, starting on the right allows the f/c to (literally!) get started.

By the time the right has run up and stabilised, ground staff will have cleared the area.

I sit to be corrected.

[fantom]

it depends.

the 320 starts the right engine first. the 330 starts the left first. it is all to do with which engine powers which hyd system for the brakes.

[Bally Heck]

SAAB 340 left engine first. Electric start and battery at left wing root giving least voltage drop on start.

[DontSink]

On the 737s, always the right one, same reason stated by Paxboy, unless if there is no APU bleed pressure for engine start, in that case no 1 must be started first!

[GoneWest]

From a "light twin" perspective, I've mulled over at least five different starts....for different aircraft....


Left first - because you can see the prop area is clear from the pilots seat...

Right first - because it's nearer the battery (aircraft specific)...

Left first - because it's furthest from the passenger doors and emergency exit (aircraft specific)...

Right first - because it's furthest away from the passenger doors and emergency exit (aircraft specific)

Alernate first start - because it then allows you to listen to the noise of each individual engine, at different times, without the noise of the other one running...

We have yet to mention the idea of "because it says so in the POH".

[Glonass]

Well, thank you all for your prompt replies.

The fact that the engine powering the brakes system is started first is an interesting perspective. At least that technical explanation satisfies me.

PAXboy, your statement is correct but I believe that would apply to some type of aircraft or operation, at least, on most jet aircrafts, the doors are usually closed previous to engine start.

Regards,

[pigboat]

'Way back when, some twins only had one hydraulic pump - on the right engine - thus the 'start right first.' Four engined aircraft had two pumps, one each on engines two and three, but the entry door was on the left, thus start number three first, followed by two, one and four.
Some twin turboprops I've flown recommended alternating starts between the right and left engines, just to verify that the de-icer boot suction was working from that engine. If you intend to start any engine out of normal sequence, make sure the ground crew knows about it. :)

[FlyaGuppy]

Left on SF-340? At the airline I worked for it was always right first. For pax loading, as stated above. That way you could get the cabin nice and cool (or hot) before people got on board.

[What-ho Squiffy!]

Right first, get the A/C up and running for the VIP's, and they are not blown away getting on board.

[Achilles]

In the bugsmasher world, it's difficult to hear the rh start to fire when the left is already deafening you.

That's my excuse...

However, type specific procedures may change this start order.

[Tinstaafl]

1. The POH says to

2. Habit

3. Variable depending on if I want to monitor one engine's output before the other contributes it's bit eg suction

[PAXboy]

Glonass,
PAXboy, your statement is correct but I believe that would apply to some type of aircraft or operation, at least, on most jet aircrafts, the doors are usually closed previous to engine start. That is true but I was thinking of the 'generality' of starts. Admitting of course that Pax cannot always be sure which is starting first. Other than by timing and knowing the typical sequence when a route or carrier is used often.

In the winter it is easier as there is often a more distinct cloud of exhaust from a cold engine than from a warm one in summer. Also, if occupying a window seat towards the rear, the sound of start will be distinct. It is then possible to judge by the other activity or push back, whether it is 2 ~ 1 or 1 ~ 2.

I was also thinking about regional airports and aircraft, where a jet bridge/air bridge is not available/used. In this case, ground staff are likely to be clearing the stairs, chocks and so forth. Also, if air stairs are in use, they take a short while to stow. If they can get the No 2 engine started, this might gain a full minute (or more?) on the sector time.

[Capt Claret]

Glonass

On the BAe146 the park brakes are powered by #2 engine, with electric hyd pump back up. The #3 eng provides the second hyd system power with PTU backup.

Pax load from the left and baggage & fuel on the right.

With engine start commencing after doors and stairs removed, start sequence in my co is #4, #3, #2, #1, simply because that's what every one expects.

If pax still boarding or head count still in progress but baggage doors closed, then start #4 & #3 to assist on time departure, or reduce delay, or if APU U/S, provide some aircon.

If pax on board and stairs removed, with approval of baggies, will sometimes start #1 & #2 first, to minimise delays.

If at an aerobridge, always start right first as they're furthest from the aerobridge.

It's all very fluid depending on the circumstances and I can't think of any reference that says 'thou shall start in this sequence'.

[BlueEagle]

In my last company, on the B744, we started 1,2,3 & 4 if possible. System 1 gave us Alternate Brakes whilst system 4 (Aux - and electrical, already selected 'on' before start),) gave us power to Normal Brakes. 2 next as that also supplies alternate brakes. System three is the least important on the ground and #3 was the engine to be shut down first if extended taxying/waiting was expected. #4, (Normal Brakes), would be last as we had not started to move under our own power yet.

Often, at out stations, an engineer unfamiliar with our companies start sequence would clear us, "4,3,2 & 1" but this was normally only in Europe.

[Dan Winterland]

In my company on the 744, we tend to start 4 3 2 1. It doesn't matter on the 744 as the brakes are powered by the aux pump number 4 and the body gear steering for pushback from aux pump number 1. If we are starting on pushback, we tend to start the engines on the inside of the turn first to give the tug a chance.

But I can see the logic in starting the right first normally. Sucking the passenger into the engines can be bad for business.

[Max Angle]

Don't know if they still do it but the P&W powered B777 starts both at the same time. Must have a mega APU. I have seen United do this at LHR a few years back, don't know about the 777 engine types.

[Flight Detent]

Hi all,
With the Classic B747, which I believe is the same, systems wise, as the -400 -:
Firstly, prior to pushback, the FE pressurizes the #4 hydraulic system with an electrically driven pump, for the aircraft brakes to work.
He also pressurizes the #1 hydraulic system with the Air Driven Pump (ADP), to power the body gear steering during the push.
Which also acts as a back-up brakes system for #4, (FE selectable), should it fail!
Even though we do start 4,3,2 &1, I've been trying to get our people to change to 1,2,3 &4, because:
#1 has the ADP running, using bleed air from the APU, which could be better used to wind up the engines a little better, especially with some of the, slightly used, APU's. Once #1 is running, the EDP output will 'auto-off' the ADP, thereby providing better bleed air pressure for the other three!
I think, in QF Classics, after #1 is started, with now no ADP running, they turn on one aircon pack during the starting of the others, but they seem to have better quality APU's than most!

Cheers

[Diesel8]

At my company, on the A-320, we start the left or #1 first, fwiw!

[compressor stall]

Fot the Shrike, well the battery is behind the wing in the fuse, so the voltage drop difference via distance is negligible.

Usually alternate starts to check if the hydraulic pumps on each engine are working.

Unless it's hot when I always start the right first as that has the aircon running off it... :D :D

[Firestorm]

SF 340.

Left engine first for a GPU start because of reasons given by BH, and because the GPU is usually just behind the right engine, thus running the risk of frying the ramp rat as he unplugs it.

Right engine for a battery start, becase the batteries are on theRHS, so less voltage drop between battery and engine. Also, some aircraft have a prop brake on the right engine which allows it to be used as an APU for electrics and heating (as well as other services) on stand.

[HotDog]

In a previous life, our start sequence on the 747 was 4, 1, 2, 3. Because of the idle thrust of these engines, if two engines are started on one side first on a wet or slippery tarmac, the tug has great difficulty in controlling the aircraft during pushback.

[BEagle]

3,4,2,1. Because that's what they did on Lancasters.....

Watched the start up of a B-52 once - levers all over the place as 2 pilots started a seemingly random selection of the 8 engines each!

Original V-bombers could start all 4 simultaneously, put all the gennies on and switch all the electro-hydraulic PFCUs on - all at the same time!

[BlueEagle]

Remember seeing a line of Vulcans one day, all quiet one minute then BANG! they wound up in no time and taxied immediately.

From first start to last airborne could only have been a few minutes. Really impressive to watch.

[spanner-do]

From a techie point of view

On our Boeing Fleet

We recommend starting the #2 first especially if using a ground (air) cart. This is because it allows for additional safety in the event of Starter Cutout failing to operate as advertised. There will be at least one isolation valve in the pneumatic system which can be closed to shut-off the air supply to the starter.

The ground cart feeds into the left air supply system.

[Divergent Phugoid!]

Would it be cos the pilot cant see the right one,but if he or she starts it first he/she will be able to hear it running, where the left he/she will be able to chuck a look over their shoulder????





:D ;) :rolleyes: :D

[PAXboy]

With regard to the V-bombers being able to crank all four together .... that would have been something to see - actually to hear. :D

As to the bod at the front being able to look back and see what was happening on the wing, is this not another reason for the video camera tucked under the rear fuselage? The point of that was from the BD problem of shutting down the wrong engine but it might also help with starts, i.e. seeing the puff/cloud of exhaust from a jet or watching the spokes go round?

The idea being a camera in a faired pod under the tail, so that it could see wing tip to wing tip. The image would be viewed on one of the glass screens by the mode selector. The camera would be able to see the undercart and it's doors, the engines and the flaps and other flying surfaces on the wing. In the event of dumping fuel, you could (probably) see it streaming away from the vent.

This was also mentioned with the problem of some carriers no longer having ground staff available for inspection of the flying surfaces response to input. Particularly so on the first rotation of the day, or after maintenance.

[BEagle]

Never flew a Vulcan when 'Mass Rapid' starts were allowed - but we still had the 'combustor' facility on most of them in the late 70s. You parked the throttles at the 50% position, selected rapid start and pressed the 4 start buttons in succession. An uncontrolled fuel/air explosion in the engine combustors spun up the engines in no time at all, as soon as they'd started and the gennies were on you started the PFCUs, 8 seconds later they'd all be running. You briefly cycled the throttles back to idle, then selected full power, turned left a few degrees off the ORP and thundered down the runway. 10-15 minutes later you'd be passing 40 000ft, still climbing...

Mark you, we've done crewroom to airborne in 7 minutes in the dear old Vickers Funbus - most of which was in the bus getting to the aeroplane!

[PAXboy]

Hi BEagle, the Mass Rapid Start sounds like big fun. Pardon my ignorance of nicknames but what was the Vickers Funbus?

[BEagle]

RAF VC10K. Because it used to take us from one fun place to another.

Rarely these days though........

[PAXboy]

Ah, I wondered if that was what you had in mind. The first aircraft I ever travelled in aged nine, the original VC-10 on a LHR ~ JNB with a fuel stop in NBO. Later we had the Super VC-10 on that run.

In it's BOAC livery, it was simply the most beautiful machine in the air. If I catch sight of one now, perhaps when motoring on the M4 near Swindon, it is enough to endanger the car and my passengers!

[78deg]

On B757

It is nessesary to test the PTU before all TOs this is accomplised by Right then Left.

[Flight Detent]

Hi SPANNER-DO,

I find your reasoning quite interesting!

Do you recall that there are, in fact, two pneumatic valves that have to be opened to supply air to the engine starter,
1/ the start control valve, the one you mentioned may malfunction, and
2/ the pylon valve, the one that opens to allow pressure to the start control valve, the one that will only allow reverse airflow, ie, towards the start control valve, when the FE selects that engine to 'ground start'.
Both close, at the same time, when the starter is released.
The isolation valves are not normally used here.

Actually, 4,1,2,3 is the best start sequence of all, taking system operation into account!

Cheers.

[747FOCAL]

Usually only one engine has a hydraulic pump that can start it after that the lit engine starts the rest. Cept inflight then you can windmill and get them going again.

[spanner-do]

Hi Flight Detent

Thanks for your response to my previous posting; in which I was refering to the original thread question of why start right engine first then the left as "Glonass" had asked.

I made the assumption (right or wrong) that we were referring to twin engine beasts.

My response was relating to our 752 and 763 fleet.

Sorry for the confusion.

Regards

Spanner-do

[Mago]

Talking about my experience, when I flew light twins (some of them) I started the left engine first when there were daylight and I started the right first when it was dark, because in the nights I couldn’t see prop when it kicked and start playing with the levers, so I had to do it by hear. I preferred to do that because when you start the right first, the passengers used to get scared faster.


When I flew B727 as a F/O, we started 1,2,3 or 3,2,1 depending on the mood, unless we where pushed back with a turn, so we started first the engine inside the turn to help the tug, especially on rainy days.

Now, on the ATR I started the Nº 2 first because it has the prop brake, so it is like starting the APU, nevertheless I (SOP) do not release the prop brake until Nº 1 is stabilized.