Avro RJ-85 Flex Thrust

[xjav8or]

Wondering if any European operators are using "Flex Thrust" takeoff settings? We have just begun using new procedures that reduce REDU takeoff power to as low as assumed temps up to 50c . This turns the great performing A/C into a real slug. Watching the end of the runway come up is something we are not used to. Mgt tells us to "have faith" all of the numbers work.. I'd like to see their faces at the end of a long t/o run with the trees comming up fast!

I'm sure their motivation is to save fuel/engines. However, as soon as we go to CLIMB NORM the N1 INCREASES... Doesn't make sense to me.

Any comments?

[safetypee]

xjav8or, it’s unfortunate that your management may not have considered the design principles behind the Avro REDU thrust setting. REDU is a ‘fixed’ flex thrust setting which is quickly selected, gives an appropriate engine life saving whilst maintaining crew confidence. The thrust rating was specifically chosen to avoid the oddities of N1 increasing with Climb selection as you have seen. I recall that the details for the REDU setting were placed in the normal checklist to encourage its use as the normal operation.

I doubt that there is any ‘real’ additional engine life benefit by using Max Flex; the EGT is slightly lower than for REDU, but the engine still has a hot cycle. There is no fuel benefit, as you still require the same amount of energy to get the aircraft in the air. Do not forget that you (or management) will get a different story from the engine manufacturer. Ultimately, it is the operator’s choice, but it should be a balance between extreme economics, safety, and a happy, confident operating crew.

When management read the small print in the AFM for winter wet/contaminated runway operations, they may get a nasty shock. Also, if you take the RJ to Aspen etc, don’t trade economics against a legal, but less than sensible and safe operation.

[xjav8or]

safetypee, Thank you for the quick and informative reply. Unfortunately, our management's scale that measures safey vs profit is not always balanced. Furthermore, they could care less about having happy crews.

[safetypee]

Oh dear, sounds like the same management that oversaw the ‘parking’ of an RJ in the car park in Knoxville and the major ‘refurbishment’ of a jet-way – or was that an attempt to change a RJ 85 into a RJ 70?

Safety culture, safety management system, human factors, are a few words that come to mind. Small changes in any, but preferably all of these programs, would save far more money than Max Flex will.