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Battery VS. APU Engine Start?  
User currently offlineBR715-A1-30 From , joined Dec 1969, posts, RR:
Posted (6 years 10 months 3 weeks 6 days 2 hours ago) and read 11470 times:

Hello Everyone.

I have flown on board many aircraft, from DC9s to 717s to 737s to ERJs to CRJs to ARJ-85s. And I was wondering, which aircraft out there do not use the APU for engine start and instead use an electric starter? The Cessna Citation, I can tell has an electric starter, as you can hear it click over. I know the ARJ-85 has an APU, but is it used to start engines?

here are a few examples. Please help me find some answers..





What say you? (Other than "Cool Videos")

26 replies: All unread, showing first 25:
 
User currently offlineOldtimer From United Kingdom, joined Aug 2006, 191 posts, RR: 1
Reply 1, posted (6 years 10 months 3 weeks 5 days 20 hours ago) and read 11340 times:

Most aircraft use air start off the APU, or in the event the APU is U/S, they use a ground air supply. The B747 would require two ground units but does normally start off the APU. The Bae 146/RJ series use electric starters using the APU or an external power supply. Some aircraft were fitted with a mod enabling the aircraft to start off internal batteries but it did cane the batteries. On early 146's they suffered badly with starter motor shaft failures due to the high torque on initial start attempt and a mod was introduced to enable a two stage soft start to save shaft wear.
ll Boeing a/c prior to 787 (jet powered) have air starters. The only pure jets I can remember with electric start were the Comets and Caravelles.
Cheers
Oldtimer



Oldtimer, I should have known better!
User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1027 posts, RR: 3
Reply 2, posted (6 years 10 months 3 weeks 5 days 18 hours ago) and read 11297 times:

Quoting Oldtimer (Reply 1):
The B747 would require two ground units but does normally start off the APU.

Interesting thing is the 757 with RB211-535E's has to have 3 Start carts for a not APU start.

David



Never under-estimate the predictably of stupidty
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9651 posts, RR: 52
Reply 3, posted (6 years 10 months 3 weeks 5 days 14 hours ago) and read 11259 times:

The 787 will be rather unique in that it will have electric starters which are actually the generators. They aren't called IDGs (Integrated Drive Generators) because they have the capability of starting the engines. The amount of electrical power during start up will put a big demand on the APU, but unlike all the other Boeing jets, it will be exclusively electrical power as there is not bleed air on the plane to be used for starting the engines.


If you have never designed an airplane part before, let the real designers do the work!
User currently offlineBR715-A1-30 From , joined Dec 1969, posts, RR:
Reply 4, posted (6 years 10 months 3 weeks 5 days 13 hours ago) and read 11255 times:

IIRC, the Boeing 717 required 2 start carts at first. I think that happened until either the MA-1A was brought out, or some kind of MOD to the APU was brought out.. Correct me if I am wrong.

[Edited 2007-11-02 22:38:22]

User currently offlineTristarsteve From Sweden, joined Nov 2005, 4010 posts, RR: 33
Reply 5, posted (6 years 10 months 3 weeks 5 days 8 hours ago) and read 11209 times:

Quoting Boeing767mech (Reply 2):
Interesting thing is the 757 with RB211-535E's has to have 3 Start carts for a not APU start.

It is not the number of carts, it is the mass flow of air.
I have started a RB211-535 with a single hose, but the system had a very high mass flow.
We have a very good ( and very old) air start cart here, and its 2 hoses have started evrything, even big engines like GE90 or Trent 800.
Anyway how do you connect three carts to a B757, there are only two connections?


User currently offlineGoldenshield From United States of America, joined Jan 2001, 6041 posts, RR: 14
Reply 6, posted (6 years 10 months 3 weeks 5 days 5 hours ago) and read 11171 times:

Most all turboprop engines are started electrically via a starter/generator with power from the APU (if equipped) or a GPU.

From what I've read, the Shorts 360 was started from an internal battery.



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 7, posted (6 years 10 months 3 weeks 5 days 4 hours ago) and read 11142 times:

Quoting Goldenshield (Reply 6):
Most all turboprop engines are started electrically via a starter/generator with power from the APU (if equipped) or a GPU.

 checkmark 

I loved working the ATR's in Atlanta!



What gets measured gets done.
User currently offlineLMML 14/32 From Malta, joined Jan 2001, 2565 posts, RR: 6
Reply 8, posted (6 years 10 months 3 weeks 5 days 3 hours ago) and read 11138 times:

I beleive even the 777 can start on electric power. Can anybody confirm this pls?

User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1027 posts, RR: 3
Reply 9, posted (6 years 10 months 3 weeks 5 days 3 hours ago) and read 11131 times:

Quoting LMML 14/32 (Reply 8):
I beleive even the 777 can start on electric power. Can anybody confirm this pls?

The engine starters on the engines are pneumatic, so no electric start, the APU has both electric and pneumatic starters.

David



Never under-estimate the predictably of stupidty
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 10, posted (6 years 10 months 3 weeks 5 days 3 hours ago) and read 11121 times:

Quoting RoseFlyer (Reply 3):
They aren't called IDGs (Integrated Drive Generators) because they have the capability of starting the engines.

Not exactly. The IDG is so called because it combines a CSD and a generator into one unit. The starter generators on the 787 will not have a CSD because they will not produce clean 400Hz power. They will produce wild voltage at varying frequency which will then be conditioned by 'power stations' located throughout the airplane.

DL757Md



757 Most beautiful airliner in the sky!
User currently offlineBAe146QT From United Kingdom, joined exactly 8 years ago today! , 996 posts, RR: 0
Reply 11, posted (6 years 10 months 3 weeks 5 days 2 hours ago) and read 11103 times:

Apropos of those videos, I would love to know why someone thought it was a good idea to hold a video camera less than a foot away from - or possibly at the lip of - the intake of the BAe/RJ in the first clip, (as is clear from the first 3 seconds of it).

Don't get me wrong - I'm not a Health and Safety wonk - but that sort of behaviour is a little Darwinian in my non-professional opinion.

Even if it's not the most dangerous thing to do around an aircraft, it shows a certain amount of contempt for risk.



Todos mis dominós son totalmente pegajosos
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 4
Reply 12, posted (6 years 10 months 3 weeks 5 days 1 hour ago) and read 11096 times:

I prefer engines with a pneumatically operated starter. Electrically operated starter motors have a very short operation time compared with pneumatic starters. Performing engine ground runs and motoring checks is more "relaxed" when you have a pneumatic start system.


This job sucks!!! I love this job!!!
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 13, posted (6 years 10 months 3 weeks 5 days 1 hour ago) and read 11096 times:

Quoting BAe146QT (Reply 11):
I would love to know why someone thought it was a good idea to hold a video camera less than a foot away from - or possibly at the lip of - the intake of the BAe/RJ in the first clip, (as is clear from the first 3 seconds of it).

If you listen carefully to the audio you can tell that the camera moves away from the intake as fuel and ignition comes on. Prior to that there is no real danger of ingestion. It wouldn't be a good idea to stick your hand in the fan but you'd be putting it rather than it being sucked in. I would say that the video showed that the videographer had a realistic sense of situational awareness and never put himself in danger.

DL757Md



757 Most beautiful airliner in the sky!
User currently offlineBAe146QT From United Kingdom, joined exactly 8 years ago today! , 996 posts, RR: 0
Reply 14, posted (6 years 10 months 3 weeks 5 days 1 hour ago) and read 11080 times:

Quoting Dl757md (Reply 13):
I would say that the video showed that the videographer had a realistic sense of situational awareness and never put himself in danger.

I hope I didn't sound like, "Stay Away From Jet Engines Or You Will Die".

I guess it's the way he bolted when the motor spun up proper.You say it means he had a good appreciation of the risk. To me it made it look like he was running away from a bottle rocket. I don't work with turbines on a day-to-day basis, (not ones that are more that 6" in diameter, anyway!), so I will defer to your analysis.  Smile



Todos mis dominós son totalmente pegajosos
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 15, posted (6 years 10 months 3 weeks 5 days 1 hour ago) and read 11080 times:

Quoting Boeing767mech (Reply 2):
Interesting thing is the 757 with RB211-535E's has to have 3 Start carts for a not APU start.

Thats for High OAT conditions.We use Two carts satisfactory.Its the Volume that matters because of the Triple spool configuration of the RB211-535.

Quoting Tristarsteve (Reply 5):
Anyway how do you connect three carts to a B757, there are only two connections?

You use Two pneumatic Jet start units.

regds
MEL



Think of the brighter side!
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 16, posted (6 years 10 months 3 weeks 4 days 20 hours ago) and read 11021 times:

Quoting BAe146QT (Reply 14):

I guess it's the way he bolted when the motor spun up proper.You say it means he had a good appreciation of the risk. To me it made it look like he was running away from a bottle rocket. I don't work with turbines on a day-to-day basis, (not ones that are more that 6" in diameter, anyway!), so I will defer to your analysis.

Being in front of a running jet is not generally healthy, but if you're got enough experience to know where the danger zone is without taking your eyes off your camera, no big deal.

The problem with the suction danger around jets is that there is no warning. Since the suction increases extremely quickly as you approach, your first sign that you've gone too far is that you're heading for the fan with nothing to stop you.

Tom.


User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1027 posts, RR: 3
Reply 17, posted (6 years 10 months 3 weeks 4 days 6 hours ago) and read 10945 times:

seeing that video reminds me when we used to do coke washes on the DC10's. Was alittle disturbing when they strap you to a truck wear a harness, while the engine is running at Flight Idie, and your holding a 10 foot wand trying to aim it at the spinner to shot the coke in the core engine and not waste it in the bypass area.

Oh yeah and all this on the night shift. But does make a cool light show seeing the sparks fly out the back.

David



Never under-estimate the predictably of stupidty
User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1027 posts, RR: 3
Reply 18, posted (6 years 10 months 3 weeks 4 days 5 hours ago) and read 10941 times:

Quoting Tristarsteve (Reply 5):
Anyway how do you connect three carts to a B757, there are only two connections?

Our 757's have 3 pnuematic connections on the manifold. two on the L/h side of the isol valve and one o the R/H side of the aircraft. I look in a pilots ops manual and they need 3 carts for hot and high fields in South America where the field elevation is over 10K.

David



Never under-estimate the predictably of stupidty
User currently offlineJetstar From United States of America, joined May 2003, 1648 posts, RR: 10
Reply 19, posted (6 years 10 months 3 weeks 3 days 21 hours ago) and read 10859 times:
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Almost all corporate jets up to the Gulfstream size have electric starters, usually a starter/generator combo. Gulfstreams and up used air starters.

On larger jet engines the air starter can provide the high torque needed to turn the engine but at a much lighter weight than an electric starter would weigh.

On corporate jets with starter/generators, the power is taken from the battery, not the APU because of the high amperage needed. A lot of the smaller corporate jets do not even have APU’s.

On the Lockheed JetStar, electric starter power was provided by 2 nicad batteries and all the APU or engine starter/generators did was charge the battery. The APU and each engine had a 300 amp starter/generator, but when the starter switch was pressed, the APU and any starter/generator on line would be disconnected until the starter switch was released. This was to prevent damage to the aircraft wires. The engine starter/generators did not have any circuit protection but the APU which had the same starter/generator that the engines had was protected by a 300 amp slow blow fuse.

The Jetstar did not come from the factory with an APU, they were installed as an aftermarket item by the completion centers on most but not all JetStars, so the pilots had to manually switch off the generator before engine start or it would blow the APU starter/generator fuse. And every JetStar carried a few spare fuses because sooner or later a pilot would forget to switch off the generator before battery starting and blow the fuse.

Some JetStars were wired with a bypass so the APU generator did not have to be manually shut off when starting off of the batteries.

At home base and sometimes on the road we would use an external electric start cart instead of the batteries, these carts had a large auto engine on them turning a generator. They are like the Hobart units welders use on their trucks for remote arc welding. Some were self powered and others had to be towed by a tug. One of the older towed start carts at our home base FBO, the generator was powered by a Chrysler Hemi head V8, that how powerful they were. When starting off of a start cart, when the pilot initially pressed the start switch, the draw on the start cart generator was enough to cause the engine RPM to drop.

One time the connector plug was worn and as the pilots were starting the 3rd engine, the plug got so hot it melted and started to arc and burn. Fortunately I was standing next to the start cart and immediately pulled the plug out. We shut down the engines and I did an inspection and found no damage to the airplane, so they restarted the engines using the batteries. Couldn’t say the same thing for the start cart, the entire plug and wires had to be changed.


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2556 posts, RR: 24
Reply 20, posted (6 years 10 months 3 weeks 2 days 18 hours ago) and read 10709 times:

Quoting RoseFlyer (Reply 3):
The 787 will be rather unique in that it will have electric starters which are actually the generators. They aren't called IDGs (Integrated Drive Generators) because they have the capability of starting the engines.

Not really a new idea. Starter/generators have been used before. Of course those on the 787 are very much larger!



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineFreshlove1 From , joined Dec 1969, posts, RR:
Reply 21, posted (6 years 10 months 3 weeks 2 days 17 hours ago) and read 10694 times:

Quoting Goldenshield (Reply 6):
Most all turboprop engines are started electrically via a starter/generator with power from the APU (if equipped) or a GPU.

From what I've read, the Shorts 360 was started from an internal battery.

Beech 1900D....Battery start unless it is really, really cold then you got to hook up the ground power to give it a little extra juice to get going.


User currently offlineKstatepilot From United States of America, joined Mar 2007, 159 posts, RR: 0
Reply 22, posted (6 years 10 months 3 weeks 2 days 15 hours ago) and read 10685 times:

Quoting Goldenshield (Reply 6):
From what I've read, the Shorts 360 was started from an internal battery.

All the 330/360's are normally started from the battery. The aircraft actually have 2 batts, the main one and then one that was only used to "assist" in starting the engines.

The only place I have used a GPU when starting the Shorts was at the UPS cargo ramp in SDF. This made for a lot cooler starts. However the GPU's are broken/run down quite a bit, so alot of the time we used the batt's.


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 23, posted (6 years 10 months 3 weeks 2 days 15 hours ago) and read 10682 times:

Quoting Goldenshield (Reply 6):
Most all turboprop engines are started electrically via a starter/generator with power from the APU

None that I can think of.....as far as bigger regional turboprops. Most all that I can think of are started from batteries....as many don't even have APU's....and those that do have APU's provide cabin air only.

[Edited 2007-11-05 19:54:13]


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineAirTran737 From United States of America, joined Apr 2004, 3704 posts, RR: 12
Reply 24, posted (6 years 10 months 3 weeks 2 days 12 hours ago) and read 10660 times:
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Quoting BR715-A1-30 (Reply 4):
IIRC, the Boeing 717 required 2 start carts at first. I think that happened until either the MA-1A was brought out, or some kind of MOD to the APU was brought out.. Correct me if I am wrong.

When the 717 first came on line at FL they all flew with a Y coupler so that two air-start units could be hooked up to it. After a while it was decided that one air-start cart would be good enough, and the company pulled the Y couplers off the planes. The BR-715 only needs a sustained 30 p.s.i. to crank the engine, which is not that much.



Nice Trip Report!!! Great Pics, thanks for posting!!!! B747Forever
25 Doug_Or : ? What types have cabin air only APUs?
26 HAWK21M : The ATP Turboprop starts using an electric starter as it does not have an APU. regds MEL
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