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Old 11-29-2017, 04:00 PM   #1
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Join Date: Oct 2017
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Exclamation EGT limits in UH-1H

Soon our implementation of EGT limits for UH-1H will go live in open beta. It is our initial implementation, and as some of you can understand it's not that easy to find documentation which explicitly says about when and how engine should degrade or even catch fire in those conditions. At the same time absence of such documentation is not enough for us to say that something should not happen. We have also comments from our SME contacts (pilots) which we considered. We are in the limitations of the simulator and we need to approximate things, therefore we say that this feature is subject to change and open for debate.

Mind you though that we have engine experts of our own and we are not going to change something just because majority wants it, but only if we receive elaborated and adequately justified explanation supported with documentation, which we will review and take time to analyse.

What you should expect:

If you are over EGT safe limits for a considerable amount of time (we will provide in-game test numbers below), it will start a cumulative degradation effect which will depend on the time and EGT temperature in which you will be flying since that cumulative degradation effect started. cumulative degradation effect will cause permanent engine performance degradation and percentage of that degradation will depend again on temperature and time.

If you drop to safe numbers before cumulative degradation effect started, you will save normal engine performance.

If you drop to safe numbers after cumulative degradation effect started, it will stop its accumulation and you will return to degraded engine performance, but accumulated cumulative degradation effect will not go anywhere. And next time you go above limits, it will start to grow again and it will bring more performance degradation.

After cumulative degradation effect reaches its limit and if you still operate engine above limits it will cause even more engine performance degradation and can cause engine fire.

Here is approximate numbers from our in-game tests (just a couple examples):

EGT temperature on gauge 645:

166 seconds (from start of over limits operation) before performance degradation (RPM will drop by ~200 in 5-10 sec);
209 seconds (from start of over limits operation) before your engine can catch fire

EGT temperature on gauge 680:
83-88 seconds (from start of over limits operation) before performance degradation (RPM will drop by ~200 in 3-6 sec);
90-95 seconds (from start of over limits operation) before your engine can catch fire

Here is numbers from manual we obtained from our SME:

400 to 610 ºC Continuous. Green Arc
610º to 625ºC Take off power. Maximum use 30 minutes. If using that temperature range more than 30 minutes it may damage the engine and maybe produce a fire.
625 to 675 Maximum 10 seconds (only for starting or acceleration) if more than 10 sec.
675 to 760 Maximum 5 seconds (only for starting or acceleration) if more than 5 sec.
760ºC Maximum. If exceeded is a HOT start or if in flight it may probably tell you have engine fire.
For normal flight conditions 625ºC is the maximum. Exceeding the limitations here may lead to engine damage, engine fire or even engine stop. With the Governor in Emergency the pilot may easily exceed the engine limits in N1 (engine structural damage beyond N1 101,5%) and EGT. Exceeding those limits could
damage the engine, produce a fire or get the engine stopped.

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