PW100 Nacelle - Additional Intake Below Engine Intake

[Papa2Charlie]

Hi all,

This is a question to those of you with PW100 / ATR experience. While standing waiting for a flight a few days ago looking at an ATR42-300, I noticed an additional intake below the primary engine intake. The intake is at the bottom of the the nacelle and slightly aft of the primary engine intake. I've added a link below to a picture of an Aer Arann ATR42 for info.

Photos: ATR ATR-42-300 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Aer-Arann/ATR-ATR-42-300/1607044/L/&sid=e99e3bb4c6e369a905c155f170f575c7)

Can someone advise what is the purpose of this intake? I've noticed it only on the early ATR's and F50's. It doesn't appear to be installed on later ATR42 or ATR72. Is it related to the standard of PW100 installed? e.g. PW120 -v- PW127 etc.?

Thanks for your help,

P2C

[Fargoo]

I don't work them but suspect its a cooling entry for the oil cooler? Later ones look like they have a moving inlet underneath thats powered open/shut?

Might be worth posting in Tech Log on these forums as there's bound to be a couple of pilots who fly them on there.

[fly_antonov]

Yes, it' s an oil cooler air intake you see there.

Usually any inlets in that area aside from the main intake are for cooling and ventilation purposes.

Oil can be cooled through fuel-oil heat exchangers and through ram air.

[Papa2Charlie]

Thanks to both of you for the replies. From the posts, I assume the early PW100's had air cooled oil coolers and the later standards had FOHE's?

Thanks again,

P2C

[fly_antonov]

Some turboprop engines have both the ram air and the FOHE cooling.

It could be that the oil cooler inlet uses ram air from the main inlet on later models, or that it was replaced by one or several less visible NACA scoops.

[lordofthewings]

The r/h engine also has provision for extra airflow due to it being used as an APU ie prop brake engaged

[Papa2Charlie]

Many thanks for the feedback folks.

All the best,

P2C