B737 SETO - Single Engine Taxi Out
 

Is the B737 NG/MAX approved for single engine taxi out? I am aware that most operators of the 737 do single engine taxi in.
I see a lot of operators do this supplementary procedure on the Airbus but it's not often heard of when it comes to the Boeing.

Can somebody please share the procedure for it as I have tried to find it online but only a few Youtube videos come up.

And extra bonus question, if you do a single engine taxi out, what are some extra considerations?
1. Engine warm up time?
2. Do you need to configure the fuel panel to prevent an imbalance (especially taxiing at large airports like MAD, CDG and AMS)?

Regarding the first question I have no idea about the 737 :8
Regarding the bonus question: on the Airbus 2 engines FBW fleets the warm-up time is pretty much dependent upon the type of engine and its thermal state, i.e. how long it has been shutoff for. You may or may not have a few minutes of warm-up time (again engine type related). For (very!) long taxi times fuel imbalance could become an issue and you must keep an eye on it.

Unrelated but when I used to be a flight instructor, I had a student who asked if we do single engine taxi in a Cessna 150... erm... yeah.

I’m not sure if it comes from Boeing specifically, but we have single engine taxi out and in approved for our NGs and Maxes. Single engine taxi out is not used all that frequently though where I work. When you factor the time to start, reconfigure, run the checklist, and bring the engine up to temp, it’s often not worth it. Also, the additional thrust needed for breakaway when single engine can cause issues in a crowded laneway, so I often don’t do it to prevent blasting the apron with FOD (although this isn’t really as big a deal on a Max compared to the NG).

We have a supplementary procedure in our AOM, the highlights of which are duplicated in the QRH Ops Info Section for day-of use. I’m not going to share a screen image from my company docs, but in short:

• Start #2 as normal and keep the APU running.
• Generator #2 is brought online, APU continues to supply power to the left AC buses.
• Packs to Auto, ISOL Valve closed, #1 bleed off, APU bleed on, #2 bleed on.
• Complete the after start checklist with responses applicable to single engine taxi.
• When ready to start the #1 engine, turn the #1 pack off and complete a normal engine start.
• reconfigure the electrical and air conditioning systems per normal procedures once the engine is started. Complete the after start checklist again, followed immediately by the before takeoff checklist to the line.

As for your specific questions.

1. The NG requires a 2 minute warm-up, while the Max requires 3 minutes.
3. Fuel balancing is an “as needed” condition in the checklist.

If you're considering SETO on the 737 NG, think about how many warning systems will activate before cabin altitude reaches 10,000 feet in case of a misconfigured air conditioning panel, and prevent you from an inadvertant unpressurised flight, and then think again whether the cost savings are worth it.

Thank you for taking the time to write this.
My operator does not approve SETO on any of the fleet (Airbus and Boeing) so we don't get to do it but it's nice to be aware of the procedure. I am already aware of the Airbus procedures but Boeing was a little mysterious.

The airline pays me to fly the aircraft the way they want it so I shall. Just wanted to have some extra knowledge. It always fascinates me how different operators <operate> the same aircraft.

How many warning systems will activate before cabin altitude reaches 10,000 feet in case of a misconfigured air conditioning panel?

Zero.
That was their point I believe. Very easy on the 737 to misconfigure the packs / bleeds leading to problems during the climb. Unless you’re looking at the cabin altitude indicator , the first you’ll know you’ve messed up is the cabin altitude warning blaring as you climb through 10,000’.

Only if you don't check the pressurisation panel configuration and pressurisation indications, as you are supposed to do, once the flaps are up...

Some airlines do engine out taxi out on 737s yes, as does mine. It's not that complicated actually. Start nr 2, then packs auto, isol valve closed, leave APU on. Then to start nr1, left pack off and start. Boeing has published engine out taxi out, and engine out taxi in, in their FCOM supplementary procedures. 3 minutes warm up time is recommended for the MAX at least when they are warm, and to have reached at least a certain minimum oil temp before takeoff.

Boeing from the start did not recommend engine out taxi, they released an FOTB due to customer demand back in the day to allow operators to create SOPs based on SPs that Boeing finally published (that as far as I know require approval from local authorities). The issue is more technical related to MEL items that are not designed with engine out taxi in mind.

There are failures of certain systems during taxi that might have special consequences depending on the setup, strange particularities might happen with ie regard to autoflight, hydraulic demand by flight controls, anti-ice systems, etc... (to which I can testify after having lost nose wheel steering during an engine out taxi). It all even boils down to a simple "can't start an engine in taxi" because in many companies, the LHSP is controlling the fuel control, but he is also the guy performing the taxi. So ie it would become a mandatory "parking brake set" to start an engine.

In short: you need extra training and even then... expect the unexpected (standard Boeing 737)

I wouldn't be happy with S/E taxi out.
1/ The side load on the nose wheel assembly, would not do the fuselage any good in the long run. Also a slippery surface and side load on the nose wheel, could cause problems
2/ Taxing out, the crew should be concentrating on the job in hand. Not playing around starting an engine that should be running before taxi..
3/ Possible shock warming.
Look after an aircraft/engine, it my help look after you.
4/ On an engine start, both should be monitoring the start. That cannot be done during taxy. When taxing BOTH pairs of eyes should.be "outside the cockpit" as much as possible.

Of course! However that could be said of any accident that involves human error with systems mis-configured.

If you're mitigating a risk versus mitigating a tiny amount of fuel burn, I know what my decision would be.

Same goes for SE taxi in - there are very few airports that my company operate into where it would achieve the desired fuel saving. We do a lot in the name of conservation that seems to be poorly thought out.

Real fuel savings come from well designed SIDs / STARs and efficient ATC / ground handling / gate coordination.

A tiny amount of fuel multiplied by x airplanes in the fleet multiplied by x sectors per day.
I can guarantee you that your CP office will not have the same opinion as you.

From what I know, the B737 NG/MAX can do single-engine taxi out, but it depends a lot on the airline's specific procedures and the situation. It's more common for single-engine taxi in, but some operators do it for taxi out to save fuel and reduce engine wear.

It is a very bad idea and I include single engine taxiing after landing as well. Certainly SETO both pilots should be monitoring the engine start. Also both pilots should have good SA on the ground and prioritize taxi routing and other aircraft. The fuel saved taxiing in is a smoke and mirrors exercise whereby bean counters come up with a fictitious amount of fuel saved also emphasizing their much heralded green credentials. In my last airline it went like this: start lever to cut off followed almost by a doubling of the fuel flow on the other engine. If you come to a halt, always possible, the amount of thrust to get going would be tripled. Some captains in order to ‘tick the box’ would ask for the start lever to cut off a few meters before arriving on stand. This action would be collated and added to those who did it ‘properly’ and at some stage later a ‘fuel saving manager’ would come up with imaginative figures and triumphant carbon saving the planet credentials. SETO, not for me, too risky on many levels.

Can you provide a reference to any incident where SETO was a factor?
CP office will tell you SETO has been happening for decades all over the planet.
"Too risky" means nothing.
Doubling of fuel flow on one engine when one is shutdown? I'm dying to ask what type you fly.

Yup, love it when pprune gets personal from all the experts out there. Firstly SETO has not been around for many years. Most CPs (sic) know the square root of foxtrot alpha. The fact that there has not been an incident does not mean that the procedure has been robustly risk assessed. I am not going down the road of saying which aircraft I fly or have flown as we are now in the standard willy waving pprune scene whereby x has eg 28,000 and ergo they are the fount of all wisdom. I have flown a mixture of Boeings including 737 and 747 ( including instructor / examiner) also Airbus A340 and instructor on A380. I currently work as an instructor for a well known manufacturer. Hope that helps. I don’t pretend to be the definitive expert but I have been around.

B737 after take-off checklist:
Bleeds - ON
Packs - Auto
...

Are we normalizing the "forgetting" of normal checklists here?

@Olster all your remarks boil down to correct training and assessing the situation. SETO/SETI is not mandatory, it's an option if the situation allows. All the rest boils down to your pilot attitude, not the procedure in itself. The procedure has a strong right to exist but needs proper training of pilots.

Fortunately some of us work for airlines, where chief pilots take the downsides of SETO seriously, and steer cleer of it for those reasons.

What also needs to be taken into account is average taxi length - it's rare to taxi out for more than 15 minutes where I fly, making any potential gains quite miniscule, compared to all the risks. Now, if you fly in USA with the 3 hour conga lines instead of A-CDM... then it makes much more sense.