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Subject: Robinson Safety Notice SN-25 extra 1.5 in MAP clarification
 
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JB77UKUser is Offline
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Posts:12

09/09/2012 3:43 PM  
Robinson just released updates to the R22 and R44 POH, main points of interest being changes to the clutch light emergency procedure (now 10 seconds and land as soon as practical unless other indications) and the section on use of carburetor heat/assist. I am trying to fully understand the implications of the new Safety Notice SN-25 on carburetor ice, where it talks about an additional 1.5 in. Hg of MAP. Read the SN here:http://www.robinsonheli.com/srvclib/rchsn25.pdf The final paragraph reads (I added emphasis): Carburetor heat reduces engine power output for a given manifold pressure. Approximately 1.5 in. Hg additional MAP is required to generate maximum continuous power (MCP) or takeoff power (TOP) with full heat applied. The additional MAP with carb heat does not overstress the engine or helicopter because power limits are still being observed. Since the engine is derated, it will produce TOP at lower altitudes even with full heat. However, avoid using more heat than required at high altitudes as the engine may reach full throttle at less than MCP or TOP. Does that mean that the pilot can pull an additional 1.5 MAP over the determined MAP limits when operating with full carb heat? Or is it saying that the additional 1.5 in. Hg will be applied even though the manifold pressure gauge shows you are at normal MAP limit for the day? Any thoughts? Many thanks in advance. Jay (R22/R44 pilot
raven5User is Offline

Posts:50

09/10/2012 6:29 PM  
If you're using full carb heat, pull an additional 1.5" more. That's how I read it. You could, though, email Robinson for clarification, since they would know best!
JB77UKUser is Offline
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09/10/2012 7:14 PM  
Yep seems it is not too clear to other pilots too, so I have sent off an email to Robinson and I will post the reply when I get it. Thanks for the thoughts - keep them coming if anyone has others.
JB77UKUser is Offline
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09/11/2012 6:14 PM  
A friend at the Robinson Safety Course just got confirmation from Tim Tucker (Chief Instructor at Robinson) that YES we can pull the additional 1.5 in. Hg (if it is there - see the bit in the SN-25 about high DA).
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Forums > JH Alternate Forum > General Helicopter Discussion > Robinson Safety Notice SN-25 extra 1.5 in MAP clarification



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