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Old 26th Sep 2010, 16:25
  #54 (permalink)  
JimL
 
Join Date: May 2003
Location: Europe
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helibuoy73,

I see I have been guilty of not reading the thread thoroughly. I missed Buitenzorg's comment that clarified exactly what you have just said:
The target torque is Bell’s poor man’s equivalent to a FLI (first limit indicator). Dependant on ambient conditions the first OEI limit the engine is expected to reach, whether engine torque, ITT or N1, is “translated” into a calculated torque value, so in case of an engine failure the pilot has only one power instrument to monitor at what will be a pretty busy time.
If you are using a CAT A helideck procedure in offshore operations, the RTOM is probably derived from two parts; the WAT part which covers the take-off profile (deck-edge clearance) and includes the first and second segment climb performance (no need to correct for obstacle clearance as the take-off segment has to be clear of obstacles) and that part which deals with the drop-down. It is likely that the drop-down portion will include wind accountability (which might have a cut-off value to prevent you exceeding the mass for the second segment climb, by using wind accountability to raise the mass).

As was previously explained, the deck-edge clearance part of the profile depends almost entirely of the energy provided by the AEO acceleration (and the higher Nr used in the take-off profile). Because the AEO Tq will be higher than the permitted OEI Tq, any failure will cause the remaining engine to go to topping - resulting in a rotor droop. Containing (restoring) the Nr will keep the engine at topping until you have reached a safe flying condition (usually just before the bottom of the descent - sometimes called Vt or target speed) at which time the engine is set to a lower limit (if 30 second power has been available) and a climb at Vtoss achieved.

Apart from adjusting the power to remove any condition of exceedence (caused by the engine moving away from its correct topping setting), the first time you have to adjust the setting will be to move from 30 second to 2 minute power (or, if there is no 30 second setting, from 2.5 minute to the next setting).

However, this still does not answer your question and that is because I can see no relevance of a Tgt Tq (as described by Buitenzorg) to an offshore profile. Perhaps your best bet then is to approach your Bell rep (there will be one in India) and pose the question to him/her.

You give the impression (from your comments) that in spite of the fact that you claim to be operating to PC1, you are not adjusting the masses for drop-down. Is that a correct assumption?

Jim

Last edited by JimL; 27th Sep 2010 at 07:48.
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