L1011 Engine Start
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L1011 Engine Start
Hi!
Is it true, that you have to start Engine No. 2 (the middle one) on L1011 aircraft first, before you can go for the other two engines?
If yes, what is the reason for that? Something with Bleed Air Distribution?
Thank you,
Bernd
Is it true, that you have to start Engine No. 2 (the middle one) on L1011 aircraft first, before you can go for the other two engines?
If yes, what is the reason for that? Something with Bleed Air Distribution?
Thank you,
Bernd
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No, it is absolutely not true that the number two engine must be started first on TriStar aircraft, altho many operators do, as a matter of course.
In fact, better bleed air distribution is available from the APU if a wing engine is the first to be started.
In fact, better bleed air distribution is available from the APU if a wing engine is the first to be started.
It’s been a while since I operated the L1011, but I seem to remember the following.
The L1011 APU bleed output was sometimes marginal to start the RB211 engines especially in hot and high conditions. Bleed pressure available to crank the engine starter was typically 1-2 psi higher for No 2 engine than for the other engines. We were told that this was due to lower duct pressure losses resulting from the shorter length of bleed ducting between the APU and the No 2 engine. After No 2 engine was started, engine bleed pressure (much better) could be used for starting the wing engines.
Therefore, we normally started the No 2 engine first.
The L1011 APU bleed output was sometimes marginal to start the RB211 engines especially in hot and high conditions. Bleed pressure available to crank the engine starter was typically 1-2 psi higher for No 2 engine than for the other engines. We were told that this was due to lower duct pressure losses resulting from the shorter length of bleed ducting between the APU and the No 2 engine. After No 2 engine was started, engine bleed pressure (much better) could be used for starting the wing engines.
Therefore, we normally started the No 2 engine first.
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Actually, FlexibleResponse, the bleed duct from the APU to the number two engine is longer, as it must go forward, then aft to the number two engine.
As to the APU being a bit weak in hot/high conditions, lets just say it was just slightly underdesigned.
As for the electric hydraulic pump C/B's, there was at one time an airworthiness directive about the pumps, and the wiring thereto, but this has long been accomplished on all aircraft by service bulletin terminating action.
As to the APU being a bit weak in hot/high conditions, lets just say it was just slightly underdesigned.
As for the electric hydraulic pump C/B's, there was at one time an airworthiness directive about the pumps, and the wiring thereto, but this has long been accomplished on all aircraft by service bulletin terminating action.
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As I remember, normally #2 was shut down after landing, saving brakes, provided the electric hydraulic pumps were on. Soon after these pumps were deemed unusable, a crew taxied in at Heathrow with all 3 running; as per habit, the Captain shut down 1 & 3 upon block-in, forgetting #2. It ran, unobserved, for 3-4 hours, as its high position & other noise (APU's, etc) made its running almost invisible, except for tape instruments in the cockpit. Rumour has it that, when this was finally discovered, the Captain was called out of rest to shut down the engine.
Actually, FlexibleResponse, the bleed duct from the APU to the number two engine is longer, as it must go forward, then aft to the number two engine.
The APU Load Compressor output joined this common duct after passing through the APU Isolation Valve situated very close to the APU compartment immediately below the No 2 Engine. This duct can also be isolated from the forward part of the pneumatic system by Aft Fuselage Isolation Valve.
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FlexResponse,
Share common ducting yes, but the aft isolation valve is normally left in the open position for engine starting.
I personally have always found that if the APU has low(er) output, starting a wing engine first has produced better results, due to higher duct pressure, and the fact that a wing engine only drives one hydraulic pump.
Some might disagree of course, however as I spent quite a long time on the 'ole TriStar, where it was hot and many times high, starting a wing engine first was preferred, if the APU was marginal.
Share common ducting yes, but the aft isolation valve is normally left in the open position for engine starting.
I personally have always found that if the APU has low(er) output, starting a wing engine first has produced better results, due to higher duct pressure, and the fact that a wing engine only drives one hydraulic pump.
Some might disagree of course, however as I spent quite a long time on the 'ole TriStar, where it was hot and many times high, starting a wing engine first was preferred, if the APU was marginal.
Re. the No 2 engine start before the others - we did, as a matter of logic. If you had a problem with either of the wing engines, it was relatively simple to attend to them. However a start problem with the No 2 required the use of a 'cherry picker' plus the obvious other access difficulties, so it was considered best to find out about it first. Otherwise you could be sitting there with the other engine/engines burning fuel while you got all the necessary bits together.
It still rates as one of the best flying machines of its type
It still rates as one of the best flying machines of its type
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block 52,
you might look at this page, this one , or in the German Lockheed L1011 Information Center.
Just seen a RAF-tanker TriStar at HAJ starting the engines, there were quite impressive smoke clouds comming from any of them during startup, although it was about ISA conditions and the plane was parked for less than 24 hours. Is this normal for starting the RB 211 ???
you might look at this page, this one , or in the German Lockheed L1011 Information Center.
Just seen a RAF-tanker TriStar at HAJ starting the engines, there were quite impressive smoke clouds comming from any of them during startup, although it was about ISA conditions and the plane was parked for less than 24 hours. Is this normal for starting the RB 211 ???
The answer to Bernd Podhradsky's question on starting No 2 engine first seems to be explained in Volume’s excellent link:
http://www.eucomairlines.de/manual/l500apen.zip
http://www.eucomairlines.de/manual/l500apen.zip
Powerplant Operations
ENGINE STARTING
The engines can be started using APU air, ground air (2 hoses minimum), or crossbleed air from an operating engine(s). Normally, the No. 2 engine is started with APU bleed air, and subsequent engines are started with crossbleed air from the operating en-gine(s). Do not mix APU air with engine bleed air or ground air.
The normal start sequence is engine Nos. 2, 1, and 3; however, this may be varied at the
captain's discretion. Particular care must be exercised to avoid exhaust blast damage from No. 2 engine. In this context local airport regulations may require that No. 2 engine be started after pushback. Any change in starting sequence should be coordinated with the ground personnel prior to initiating engine start.
……
Optimizing Air Supply
If air supply for start is marginal, close the engine HP air shutoff valve to ensure maximum air supply to the starter.
Depending on start air source, accomplish the following:
For starts using APU air:
• Start No. 2 engine first because duct air pressures are generally 1 to 2 psig higher than
when starting a wing engine from the APU.
• When starting No. 2 engine, if air supply is marginal, close the crossbleed valves to
ensure maximum air supply to the starter.
• Minimize APU generator load to prevent electrical demands from taking priority over
air supply. For each lOkW reduction on APU generator load, the available engine
starter torque is increased by approximately 4%.
• Operate an air conditioning pack during engine start to reduce surging of the APU
load compressor. This added load fully closes the surge control * valve and all
dumping ceases. However, if the duct air pressure is reduced by more than 2 psig with
the pack on, the resulting pressure may be insufficient for a proper engine start. In this
case, the pack should be turned off and the start continued, despite the air pressure
fluctuations.
For starts using ground air or crossbleed air :
• Turn off all packs.
• Check crossbleed valves open.
• When using ground air, start a wing engine first, because for a given duct air pressure
the wing engines may spool-up faster than No. 2 engine.
ENGINE STARTING
The engines can be started using APU air, ground air (2 hoses minimum), or crossbleed air from an operating engine(s). Normally, the No. 2 engine is started with APU bleed air, and subsequent engines are started with crossbleed air from the operating en-gine(s). Do not mix APU air with engine bleed air or ground air.
The normal start sequence is engine Nos. 2, 1, and 3; however, this may be varied at the
captain's discretion. Particular care must be exercised to avoid exhaust blast damage from No. 2 engine. In this context local airport regulations may require that No. 2 engine be started after pushback. Any change in starting sequence should be coordinated with the ground personnel prior to initiating engine start.
……
Optimizing Air Supply
If air supply for start is marginal, close the engine HP air shutoff valve to ensure maximum air supply to the starter.
Depending on start air source, accomplish the following:
For starts using APU air:
• Start No. 2 engine first because duct air pressures are generally 1 to 2 psig higher than
when starting a wing engine from the APU.
• When starting No. 2 engine, if air supply is marginal, close the crossbleed valves to
ensure maximum air supply to the starter.
• Minimize APU generator load to prevent electrical demands from taking priority over
air supply. For each lOkW reduction on APU generator load, the available engine
starter torque is increased by approximately 4%.
• Operate an air conditioning pack during engine start to reduce surging of the APU
load compressor. This added load fully closes the surge control * valve and all
dumping ceases. However, if the duct air pressure is reduced by more than 2 psig with
the pack on, the resulting pressure may be insufficient for a proper engine start. In this
case, the pack should be turned off and the start continued, despite the air pressure
fluctuations.
For starts using ground air or crossbleed air :
• Turn off all packs.
• Check crossbleed valves open.
• When using ground air, start a wing engine first, because for a given duct air pressure
the wing engines may spool-up faster than No. 2 engine.
Last edited by FlexibleResponse; 12th Aug 2004 at 09:16.
I agree with Flexible Response. My employer, who operated 18-19 L1011's in very hot conditions, always started No. 2 when using the APU. After No. 2 was running the APU bleed valve was closed (the APU bleed air could not be mixed with other air sources as it might surge) and No. 2 bleed air was then used to start 1 and 3. The reason was pressure drop due to ducting length. The APU fed into the aft fuselage ducting below the horizontal stabiliser (where the APU was installed). This was the same duct used by No. 2 engine. If using ground air a wing engine was usually started first.