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Embajador3
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Taxiing with 1 engine

Tue Nov 26, 2019 9:09 am

I remember seeing how many US airlines were using only one engine when taxing. Is this something most airlines do? I don´t recall seeing that in Europe, and most certaintly, the airline where I work does not allow such a thing.
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Armodeen
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:10 am

Very very common practice in the UK.
 
paullam
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:11 am

Embajador3 wrote:
I remember seeing how many US airlines were using only one engine when taxing. Is this something most airlines do? I don´t recall seeing that in Europe, and most certaintly, the airline where I work does not allow such a thing.


EasyJet and SAS do it in Europe. I’ve seen Pegasus and KLM do it as well.
Qatar even use single engine taxi on their 777.
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Embajador3
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:17 am

Armodeen wrote:
Very very common practice in the UK.

Do UK airlines whom operate turboprop aircraft use one engine for taxiing too?
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Armodeen
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:24 am

Embajador3 wrote:
Armodeen wrote:
Very very common practice in the UK.

Do UK airlines whom operate turboprop aircraft use one engine for taxiing too?


Flybe certainly does, it’s obviously very easy to see on a prop.
 
anrec80
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:28 am

Yes, this is common among U.S. majors. I am also wondering - are economic advantages of this even noticeable? It seems to put more wear on one engine vs the other.
 
KFTG
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:31 am

Please let the pilot fly the airplane.
 
CHRISBA35X
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:10 am

Its SOP at KLM fleet wide, certainly at AMS, not sure about other airports but every KLM flight I've taken has been this way.

I've been on FlyBe Embraers that do it as well.

Its an odd sound to hear the plane land on the Polderbaan and be tootling along toward the terminals and to hear them shut down the number one engine.
 
sevenair
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:17 am

Qantas link do it on the Dash.
 
Eikie
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:19 am

anrec80 wrote:
Yes, this is common among U.S. majors. I am also wondering - are economic advantages of this even noticeable? It seems to put more wear on one engine vs the other.

The wear on the other engine is minimal at best.
Taxiing is most often done with both engines on idle (minimum thrust) and even then there is breaking needed not to exceed the maximum taxi speed. Of course higher weights and accelarations required slightly more power.

Shutting down 1 engine might ask more of the other when accelerating, but on long streches the remaining engine, in that idle position, is most of the time enough to keep taxiing.

So it asks a little bit more of the remaining engine, but saves on breaking and fuel.
 
Ronaldo747
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:23 am

Vueling in BCN did it as well at my flight three years ago, quite short taxi to 25L but long queue for departure though.
 
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brianK73
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:41 am

It's a standard operating procedure in my C152.
 
cedarjet
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:56 am

On some planes you have to because the engines generate so much residual thrust (what comes out when the throttles are shut, aka flight idle) that you’re riding the brakes to stop it accelerating otherwise, which wears the brake pads and can overheat the brakes. P&W powered 747s especially.
brianK73 wrote:
It's a standard operating procedure in my C152.

Ha we must fly for the same airline, SOP on the PA-28 too!
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
KFTG
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:57 am

brianK73 wrote:
It's a standard operating procedure in my C152.

Sounds dangerous.
 
GBNWB
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 11:00 am

BA do it with the Airbus. Only risk is not starting it early enough to get heat in the engine. No more of a risk than getting to the runway without the numbers having arived yet though :-D
 
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AirKevin
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 12:08 pm

anrec80 wrote:
Yes, this is common among U.S. majors. I am also wondering - are economic advantages of this even noticeable? It seems to put more wear on one engine vs the other.

I guess if the taxi is long enough, it would make a significant difference. I was on a Delta 757 back in 2007 that did a single engine taxi. Taxi time to runway 31L was 58 minutes, and the second engine was started when we were on 22L.
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pdp
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 12:09 pm

GBNWB wrote:
BA do it with the Airbus. Only risk is not starting it early enough to get heat in the engine. No more of a risk than getting to the runway without the numbers having arived yet though :-D


I'm assuming this is more of a risk than for say EZY because of how long it takes the IAEs to fire up?
 
GBNWB
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 12:12 pm

pdp wrote:
GBNWB wrote:
BA do it with the Airbus. Only risk is not starting it early enough to get heat in the engine. No more of a risk than getting to the runway without the numbers having arived yet though :-D


I'm assuming this is more of a risk than for say EZY because of how long it takes the IAEs to fire up?


Indeed, I think EZY start theirs passing Q when headed for 08R at LGW.
 
BA777FO
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 2:59 pm

The A320 can single-engine taxi out, starting the other engine closer to the runway. Boeing do not have a procedure for this.

Boeing and Airbus can shut engines down on the taxi in. The 747 can taxi in on 2 engines, I believe the A380 can too.

After landing, at weights below 190 tonnes, the 777-200 will quite happily gain speed at idle on a single engine. The GE90s require a 3 minute cool down after landing, the RR Trents only need 1 minute.
 
DiamondFlyer
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 3:18 pm

BA777FO wrote:
The A320 can single-engine taxi out, starting the other engine closer to the runway. Boeing do not have a procedure for this.

Boeing and Airbus can shut engines down on the taxi in. The 747 can taxi in on 2 engines, I believe the A380 can too.

After landing, at weights below 190 tonnes, the 777-200 will quite happily gain speed at idle on a single engine. The GE90s require a 3 minute cool down after landing, the RR Trents only need 1 minute.


Just because Boeing doesn't have a procedure for it, doesn't mean that an airline can't do it on a Boeing airplane..
From my cold, dead hands
 
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Starlionblue
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 3:40 pm

anrec80 wrote:
Yes, this is common among U.S. majors. I am also wondering - are economic advantages of this even noticeable? It seems to put more wear on one engine vs the other.


According to our beancounters, even a minute or two of single engine taxi means noticeable savings.

KFTG wrote:
Please let the pilot fly the airplane.


?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
BA777FO
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 8:56 pm

DiamondFlyer wrote:
BA777FO wrote:
The A320 can single-engine taxi out, starting the other engine closer to the runway. Boeing do not have a procedure for this.

Boeing and Airbus can shut engines down on the taxi in. The 747 can taxi in on 2 engines, I believe the A380 can too.

After landing, at weights below 190 tonnes, the 777-200 will quite happily gain speed at idle on a single engine. The GE90s require a 3 minute cool down after landing, the RR Trents only need 1 minute.


Just because Boeing doesn't have a procedure for it, doesn't mean that an airline can't do it on a Boeing airplane..


Good luck getting your FCOM approved by the regulator in that case.

Can you point me towards any airline that uses a single-engine taxi out procedure on a Boeing aircraft?
 
BA777FO
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:02 pm

Starlionblue wrote:
anrec80 wrote:
Yes, this is common among U.S. majors. I am also wondering - are economic advantages of this even noticeable? It seems to put more wear on one engine vs the other.


According to our beancounters, even a minute or two of single engine taxi means noticeable savings.


30 minutes taxi fuel for a 777-200 is just under 800kg of fuel. So 1.6 tonnes per hour - 26kg of fuel per minute or 13kgs per engine per minute.

What's the price of 16 litres of Jet A1? ~$15? With an engine shut down for 5 minutes that's $75. Across an airline with 50 777s that's $3,750 per sector or $7,500 per day. ~$2,500,000 over the course of the year accounting for downtime for maintenance for a fleet that size. Not huge in the context of revenues of billions but the accountants will love it nonetheless.
 
GalaxyFlyer
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:03 pm

We did single and two engine taxing in the mighty Boeing Tri-motor.
 
DiamondFlyer
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 9:14 pm

BA777FO wrote:
DiamondFlyer wrote:
BA777FO wrote:
The A320 can single-engine taxi out, starting the other engine closer to the runway. Boeing do not have a procedure for this.

Boeing and Airbus can shut engines down on the taxi in. The 747 can taxi in on 2 engines, I believe the A380 can too.

After landing, at weights below 190 tonnes, the 777-200 will quite happily gain speed at idle on a single engine. The GE90s require a 3 minute cool down after landing, the RR Trents only need 1 minute.


Just because Boeing doesn't have a procedure for it, doesn't mean that an airline can't do it on a Boeing airplane..


Good luck getting your FCOM approved by the regulator in that case.

Can you point me towards any airline that uses a single-engine taxi out procedure on a Boeing aircraft?


Numerous US airlines...
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BA777FO
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 10:44 pm

DiamondFlyer wrote:
BA777FO wrote:
DiamondFlyer wrote:

Just because Boeing doesn't have a procedure for it, doesn't mean that an airline can't do it on a Boeing airplane..


Good luck getting your FCOM approved by the regulator in that case.

Can you point me towards any airline that uses a single-engine taxi out procedure on a Boeing aircraft?


Numerous US airlines...


On their Airbus aircraft, yes. So do European airlines. If Boeing has introduced a single engine taxi out procedure for the 737 it must have been within the past few years. They certainly don't have one for the 777 or 787.
 
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Starlionblue
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 11:01 pm

AFAIK our Boeings do single-engine taxi in. Same as we do on the 'bus.
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LH707330
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Re: Taxiing with 1 engine

Tue Nov 26, 2019 11:33 pm

Do most airlines specify which engine needs to be shut down for the single-engine taxi? On quads, do they shut down 1 and 4 and leave 2 and 3 running?

I met a guy who said his carrier always specified that one engine on a 320 should be shut down, so the other got more wear, and their spool-up would be a bit different.
 
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AirKevin
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Re: Taxiing with 1 engine

Wed Nov 27, 2019 12:05 am

BA777FO wrote:
DiamondFlyer wrote:
BA777FO wrote:
The A320 can single-engine taxi out, starting the other engine closer to the runway. Boeing do not have a procedure for this.

Boeing and Airbus can shut engines down on the taxi in. The 747 can taxi in on 2 engines, I believe the A380 can too.

After landing, at weights below 190 tonnes, the 777-200 will quite happily gain speed at idle on a single engine. The GE90s require a 3 minute cool down after landing, the RR Trents only need 1 minute.


Just because Boeing doesn't have a procedure for it, doesn't mean that an airline can't do it on a Boeing airplane..


Good luck getting your FCOM approved by the regulator in that case.

Can you point me towards any airline that uses a single-engine taxi out procedure on a Boeing aircraft?

I know Delta has done it, I've been on two 757 flights where this happened.
LH707330 wrote:
Do most airlines specify which engine needs to be shut down for the single-engine taxi? On quads, do they shut down 1 and 4 and leave 2 and 3 running?

I met a guy who said his carrier always specified that one engine on a 320 should be shut down, so the other got more wear, and their spool-up would be a bit different.

On the 747, engine 3 is the one that gets shut down when taxiing in. You don't want to shut down 1 or 4 because the hydraulics for those engines are tied to the brakes and steering. Not sure about other planes
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Starlionblue
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Re: Taxiing with 1 engine

Wed Nov 27, 2019 1:27 am

LH707330 wrote:
Do most airlines specify which engine needs to be shut down for the single-engine taxi? On quads, do they shut down 1 and 4 and leave 2 and 3 running?

I met a guy who said his carrier always specified that one engine on a 320 should be shut down, so the other got more wear, and their spool-up would be a bit different.


Not an engineer, but methinks the difference in wear is probably minimal if one engine is shut down earlier than the other every flight. As mentioned above the engines are at idle or just above idle while taxiing. Besides, engines are "mixed" all the time, as in one might have been hanging on the wing for years and the other one might have just been replaced. They're going to be different, but FADEC makes it transparent to the user, so to speak.

Which engine you shut down is somewhat dictated by the systems architecture. On the A350, the hydraulic systems are symmetrical (both systems have one pump in each engine) so it doesn't make a difference which engine is shut down. Take your pick on the day, perhaps considering the direction of any tight turns.

On the A330, on the other hand, shutting down engine 2 is recommended because alternate braking and the brake accumulator are on the blue hydraulic system, which is powered by engine 1 only. Pretty unlikely you'll lose normal braking, and you'd still have the accumulator. But just in case.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
RetiredWeasel
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Re: Taxiing with 1 engine

Wed Nov 27, 2019 3:14 am

AirKevin wrote:
BA777FO wrote:

On the 747, engine 3 is the one that gets shut down when taxiing in. You don't want to shut down 1 or 4 because the hydraulics for those engines are tied to the brakes and steering. Not sure about other planes


At NW on the 744 taxing out for takeoff with #3 shutdown was often done if the aircraft wasn't real heavy. It was referred to as "Delayed Engine Start". And right out of manual, the company/Boeing said that one minute of engine out taxi is worth 3.7 gallons of fuel. Multiply that by the number of 744 flights per year and it added up I reckon.
 
Chemist
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Re: Taxiing with 1 engine

Fri Nov 29, 2019 6:46 am

WN taxis out their 737s on single engine all the time. I often hear the second engine spooling up as we near the end of the taxiway before the turn onto the runway.
 
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zeke
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Re: Taxiing with 1 engine

Fri Nov 29, 2019 10:35 pm

Chemist wrote:
WN taxis out their 737s on single engine all the time. I often hear the second engine spooling up as we near the end of the taxiway before the turn onto the runway.


Crazy if true, engines need a few minutes after start to become thermally stable for maximum thrust to be applied.
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Chemist
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 6:06 am

zeke wrote:
Chemist wrote:
WN taxis out their 737s on single engine all the time. I often hear the second engine spooling up as we near the end of the taxiway before the turn onto the runway.


Crazy if true, engines need a few minutes after start to become thermally stable for maximum thrust to be applied.


I could always be mistaken but have clearly heard what sounds like second engine spool up through the octaves on late taxi to the runway. What I haven't done is measured the time between engine start and takeoff. While sometimes at my local airport we turn right onto the runway and go, there are other times we hold at threshold, or line up and wait. So perhaps there is a correlation with waiting after engine#2 start and takeoff. Just don't know, I'll try to pay some attention on my next few flights. I have an upcoming flight next week, and then in late December and another in early January. All on WN.
 
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Francoflier
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 6:50 am

I was flying on a major European A320 operator recently and we definitely taxied out on a single engine. The other one was noticeably started on the taxi out later (spool up sound, lights flickered from power transient, oh, and the bloody dog finally stopped barking..). It was started well in time to allow proper warm up before takeoff (long taxi). From the expeditiousness and flow of the whole thing, it very much seems like standard ops at this particular airline.
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longhauler
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 7:15 am

Chemist wrote:
zeke wrote:
Chemist wrote:
WN taxis out their 737s on single engine all the time. I often hear the second engine spooling up as we near the end of the taxiway before the turn onto the runway.


Crazy if true, engines need a few minutes after start to become thermally stable for maximum thrust to be applied.


I could always be mistaken but have clearly heard what sounds like second engine spool up through the octaves on late taxi to the runway. What I haven't done is measured the time between engine start and takeoff. While sometimes at my local airport we turn right onto the runway and go, there are other times we hold at threshold, or line up and wait. So perhaps there is a correlation with waiting after engine#2 start and takeoff. Just don't know, I'll try to pay some attention on my next few flights. I have an upcoming flight next week, and then in late December and another in early January. All on WN.


Also consider that the remaining items on the After Start Checklist must be completed, as well as the Before Takeoff Checklist. None of which can be done until the second engine is started. This can take around 5 minutes or so. A bit risky that close to the runway.

Not to mention, ATC (rightfully) gets more than a little miffed if you’re not ready when it’s your turn.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
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longhauler
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 7:21 am

Francoflier wrote:
oh, and the bloody dog finally stopped barking.


When done per Airbus SOPs, a single engine taxi should not result in the PTU running, other than the test during engine start. However, the Yellow Electric (hydraulic) Pump can get a little irritating, as it will be running. It is a high pitched “whine” heard around the middle of the cabin.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
Chemist
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 8:20 am

longhauler wrote:
Chemist wrote:
zeke wrote:

Crazy if true, engines need a few minutes after start to become thermally stable for maximum thrust to be applied.


I could always be mistaken but have clearly heard what sounds like second engine spool up through the octaves on late taxi to the runway. What I haven't done is measured the time between engine start and takeoff. While sometimes at my local airport we turn right onto the runway and go, there are other times we hold at threshold, or line up and wait. So perhaps there is a correlation with waiting after engine#2 start and takeoff. Just don't know, I'll try to pay some attention on my next few flights. I have an upcoming flight next week, and then in late December and another in early January. All on WN.


Also consider that the remaining items on the After Start Checklist must be completed, as well as the Before Takeoff Checklist. None of which can be done until the second engine is started. This can take around 5 minutes or so. A bit risky that close to the runway.

Not to mention, ATC (rightfully) gets more than a little miffed if you’re not ready when it’s your turn.


This is all out of BUR. I have flown about 150 segments out of this airport over the past 5 years mostly due to work. I would not say that second engine start on taxi is a majority of the time, but it's not rare, either. Any WN crew online to verify this? I'll pay attention to the timing on my next few flights should they taxi on one engine.
 
Tristarsteve
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Re: Taxiing with 1 engine

Sat Nov 30, 2019 11:03 am

When I worked in engine development at BEA at LHR in 1970, the airline had started shutting down the nbr three engine on the Trident after landing. I was involved in some check of the turbine blades by boroscope, in the days when there were no boroscope ports or hand turn drive on the Spey engines. (We removed the starter motor and an ignitor plug!)
Soon after it was noticed that the Nbr 3 engines were failing much more often than the others, and the experiment was abandonded. Bit ahead of our time!

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