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A320 CFM Takeoff Thrust Problems


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Hi everyone. I am having a huge problem with airbus A320 CFM engines when taking off from SKBO (Eldorado International Airport, in Colombia). Basically what happens is the aircraft does not provide enough thrust to takeoff and successfully fly the SID when taking off from runways 13R or 13L if the TOW is anything above 71 tons. The procedure at Bogotá is to takeoff, reduce to climb power when at 800ft AGL (that would be 9200ft ASL), and keep climbing while maintaining v2+10 on a turn, accelerating at 11,000ft all the way to 230knots, and then continue climbing to be at 12,000 or higher at SOA (for SID's with a right turn) or at GUXUN (for SID's with a left turn). The problem is, if you try doing the procedure on the A320 with anything more than 71 tons of TOW, it will simply not be able to climb and will not reach SOA or GUXUN at 12,000 ft and 230 knots. Even if you takeoff with TOGA, it will not work. I've talked to a real world Avianca A320 pilot about this, and he told me it's a problem with my simulator because in real life A320 can perform the departure comfortably even with max TOW. Yes, the airport elevation is high (8360ft) but the runway is sufficiently long (3800 meters). Please help, I don't know if my issue is just in my simulator or it occurs in everyones airbus.

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Well, the topic is quite interesting. But it also addresses the question concerning equipment used during take offs from high elevation runways.

According to FCOM03 and FCTM engine bleed should be turned of during take off from high elevation runways. As far as I know, a high elevation runway is situated above 4900 feet ASL.

The reason is that hot air for the air condition, as well as for anti icing is ducted from the engine to the equipment, thus reducing take off thrust.

So may be I would try taking off in late spring with cavok conditions with Engine Bleed off, AC packs off, anti ice off first, to see what happens. After that you can fine tune equipment for other weather conditions.

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  • 1 month later...

Hi, thanks for your response. Just gave what you suggested a try, but it didn't work. The problem here is not during takeoff roll. When in lower TOW's, the aircraft performs the SID correctly. But in high TOW's, over 70 tons, it takes off with TOGA on a very low FPM (1200-1500), and when reaching 9200 and reducing to climb power it can no longer climb effectively to reach SOA at 12,000 or higher. It's a relatively complicated procedure, performing a turn right after takeoff to avoid mountains and a NAP at the same time, but real airbus can fly it and overcome restrictions comfortably even at max TOW. I would suggest you to give it a try, reducing to climb thrust at 9200 and accelerating at 11,000 with an a320 at max tow. I feel like this issue turns more towards a software malfunction since what you duggested didn't work.

Any further help appreciated!

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Hi,

you can climb after takeoff with manually set V/S and/or speed ( max 185 kts as first restriction) and Flaps 2 - 1F.

In the charts you can see how much ft/Min you need for xx% climb gradient. For 180 to 210 Kts GS you need 1500 - 1800 ft/Min

I startet with Packs off. At SOA i had 12000+, thereafter i change to managed speed (or as required)

Complete managed after takeoff, ihad also problems.

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Thanks FraPre for your response, I would like to ask if you performed the noise abatement procedure (reducing to climb thrust at 9200, maintaining v2+10 until 11,000 and accelerating at 11,000). That seems to be what made it so hard to meet the restriction at SOA. Also, did you try the takeoff at max TOW? The airbus doesn't seem to have trouble with the SID at low TOW's

Thanks, good night everyone. 

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Hi,

today i´ve performed an new test flight (without real reference and rwy 13R forced).

The MTOW may have different limits.

* Structural Airplane Limit - published as MTOW in the documents

* MTOW limited by MZFW

* MTOW limited by MLW

* MTOW limited by Performance (airport data, weather, flap setting)

 

So when we speak of MTOW, we must distinguish, what determines the respective MTOW.

In case of an flight from SKBO to .... (i planned SAEZ), not make the MZFW, MLW, structural MTOW the limit, but the performance. 

For my flight with real weather yesterday, was the limit determined by performance data.

You can see, for an flaps 2 takeoff the limit for my loading is lower as the actual weight, an takoff is not possible. With flaps 3 the performance limit is sufficient for my weight.

TOPCAT is´nt for the Aerosoft Bus, but í take it with the feelthere airbus (little variations are therefore possible). TOPCAT calculated 99.1 % N1, but I only reach 97,8.

 

With this (TOW 75591 Kg)  I once flew, all managed. At 0,4 DME SOA i´ve reached 13000 ft ;-).

After takeoff with flaps 3, passing the THR RED / ACC ALT  and Speed above F Speed, i set flaps 1, than accelerate via 185 to 230 and retracted with passing S Speed to flaps 0 (green dot was 220, otherwise I would have left flaps 1).

Some circumstances are due to the test.

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