Reduced TIT to save Turbines

[bertengineer]

I am doing a paper for ERAU about reduced TIT to save engines on T56. I was with a unit that flew 1010 and we had minimal engines changes due to turbine failures, compared to a fleet squadron that was flying at a recommended 932. I am looking for any information that may prove my claim..however I am open to any information that may prove me false also. It is a masters paper and I am just trying to get info.

1. flight hours between engine removal and replacement due to turbine failure, cracks

2. effect of constant touch and go on engine performance compared to cruise flight

Any input is greatly appreciated.

Thanks,

Rick

[tenten]

Have you got access to this booklet?

Somehow it touches the issue.

[trev130eng]

Service news Volume 14 No.1 has a good article on conserving turbine life by flying at reduced TIT.

[kingair200]

1010 for TO I hope, you cruise at 1010 you will not have much of a turbine left at TBO.

here some good numbers from TFK 1010 TO 971 Climb 931 cruise

[Dave in WV]

If you are talking about -15 engines the reduced power TIT is 970 unless it has been changed. 932 is -7 engine max continuous TIT for cruise. I can't give stats but I know at least 2 ANG units had H2s and flew them at 1010 all the time and they had more engine changes for tubines than the units that flew at 970. To do the reduced power for more turbine life the correct way is to chose an altitude you can get 280 TAS in an E model @ 900 TIT and 290 TAS in an H model @ 970 TIT but most units went for 300 TAS in the H models. As the speed increases you pull the power back to maintain the TAS.

[P3_Super_Bee]

This is a sham the going on in the regular VP Navy (P-3 / T-56-14). They are limited to 940(IIRC)... In Executive Transport, we flew at 1010 on a normal basis. We didn't change out turbines any more then the regular VP guys. Wish I had tech info for you.

[jetcal1]

Perhaps it would be a good idea to contact any manufacturer that provides derated or flat rated engines and see what they suggest for HSI/TBO intervals for those engines versus the original rating. That would be a great indication of what a lower TiT does.

As far as the VIP flights, perhaps the engines experienced more cycles than a patron mission profile.

I would imagine that a B737 making flights between Dallas and Tulsa would have more cycles and less time than a B737 flying between Dallas and LA. More cycles, less hours is still a potentially degraded hot section and less time on wing.

It’s not just time or temp, but cycles as well.

[RZHill]

That is right, the varing temperature with tactical flying versus drone flying sure make a difference.

Face it if southern air flew there 130's like a school squadron they wouldn't have the high time 130's the old saying, go fast for a short time , go slow for a longtime.

RZ

[Mcmuffin07]

i havent heard anything about the temps changing, but 1010 is max continuous for a -15 engine, where 932 is max continuous for a -7.

[BDizzle]

For -15 motors the Vol.3 asks us to use 970 for training. The 1-1 tells us "climb at reduced power of 970C TIT is recommended to prolong engine life."

[KJamison]

Bertengineer, I flew EC's during test flights. We would use 1010 all the time. The trick was to set 1010 at the end of the runway and not touch the throttles again until coming down to land. We racked up lots of hours and not a single problem. RZ is totally right on not the temp you use but how you fly. 1010 at 300 with huge temperature changes on the throttle. Sulfur and micro-fod of the blades at high temperatures, loading and unloading the engine, Assault landings, touch and go's, three eng go arounds, is a completely different kind of use than take off at 1010 and don't touch the throttles again until time to land. It seems difficult for folks to see the difference. They always seem to refer you to the Service News which is good data to booster a case for conserving turbines. I sure would like to see some data on the EC world vs the Tac-training world and the Iraq world of flying. I think you might see some interesting info.

Good luck and I am following you with the Masters at ERAU. Gotta love "ERNIE".

[Steve1300]

A few times now, while speaking with the guys who teach the engine maintenance course for Allison (now Rolls Royce), I would get told about how long the 501D (T56) engines last when used as electrical generator power plants. While it is true that varying the temps constantly creates problems and that higher temps have more impact on shortening the life of the hot sections, the fact still remains that operating this engine at 850 TIT allows the engines to last 30,000 hours. Now, I know my memory isn't perfect, but the number that they gave me up at the Allison school stuck with me. Compare 30,000 hours versus 5000 hours when used as a Herk engine!

The people who manufacture these engines say that lower temps are better and that "thermal shock" is destructive. I believe them. Sure wish we could get 30,000 hours on our engines......