Cat A Offshore Helideck procedure of AW139

[twinbird]

I wonder if we are able to do Part E and I, Offshore Helideck procedure at the elevated Helideck on the land.
The name of the procedure is Offshore Helideck but Maximum Altitude for Offshore Helideck CAT A Take-Off as well as Landing is 5000 ft Hp/Hd.
I don't think there is such a high Offshore helideck and I think the procedure above mentioned is not only for real offshore helideck.

The only problem I have now is that there is the description on Part E Page S12-E5 as below;

If the Take-Off Weight would require a drop down, during a single engine failure, it is assumed that the height of the Elevated Helideck
is greater than the Drop Down plus a height clearance margin as required by the Competent Authorities, and that there are no obstacles
beyond and below the deck edge.

[gipsymagpie]

The limit states 5000ft hp or hd. You could get to 5000 ft Hd (density altitude) in a 50 Deg Celsius OAT with a relatively high humidity at sea level. I suspect that's what that limitation is about. Not sure I understand the remainder of your query.

[212man]

The limit states 5000ft hp or hd. You could get to 5000 ft Hd (density altitude) in a 50 Deg Celsius OAT with a relatively high humidity at sea level. I suspect that's what that limitation is about. Not sure I understand the remainder of your query.
I’ve never seen humidity in a performance graph?

[gipsymagpie]

I’ve never seen humidity in a performance graph?
Fair point. Whilst it does have an effect, the certification specifications (CS-27/29) do not require it to be considered. It was historically considered when performance margins were tighter

Pprune discussion - humidity and density altitude (http://www.pprune.org/rotorheads/318977-effect-humidity-turbine-engine-perf.html)