When doing a forward slip to landing in a Cirrus, is there a flap extension restriction?
andy
In reply to:
When doing a forward slip to landing in a Cirrus, is there a flap extension restriction?
Andy,
Not that I know of. I have certainly done this a number of times.
A search of the POH seems to confirm it. Section 3 (Emergency Procedures), in the section on Emergency Descent, says “The fastest way to get the airplane down is to lower flaps to 100%, put it into a turning forward slip, and point the nose down.” Granted, this is for an emergency. The only other time a slip is mentioned is in the context of another emergency – slipping to keep the flames away from the fuel tank in case of a wing fire.
Even so, I believe that if there were any constraint, it would be listed in Section 2 (Limitations), and I can’t find any mention of one. (Gotta love the POH in searchable PDF format!) The FAA is nothing if not consistent about these things… and the Skyhawk POH I just looked at states clearly that the pilot should AVOID SLIPS WITH FLAPS EXTENDED. I can understand why - the 172 makes a funny burbling noise when you slip it with flaps hanging out. [;)]
Mike.
The restriction on slipping is not in relation to the flaps but the paragraph below is quoted from the POH section on crosswind landings. I suspect the limitation on slipping is because of possible fuel starvation since slipping could prevent feeding from the main wing tank to the fuel collector.
Crab into the wind until in ground effect. Then take out any crab angle with rudder. Avoid prolonged slips.
The 172 makes a funny burbling noise when you slip it with flaps hanging out.
Funny, I always thought it was the passengers making that burbling noise…
I suspect this is a concern with engine cooling since airflow into the engine is not necessarily even between the two cylinder banks. The SR22 slips wonderfully. The 172 disrupts airflow over the elevator when flaps are down and hence the restriction.
Below is a quote from section 7 of the POH describing the fuel system.
When the fuel tanks are 1/4 full or less, prolonged
uncoordinated flight such as slips or skids can uncover the
fuel tank outlets. Therefore, if operating with one fuel tank dry
or if operating on LEFT or RIGHT tank when 1/4 full or less,
do not allow the airplane to remain in uncoordinated flight for
periods in excess of 30 seconds.
Thanks for the correction. Now that you mention it I remember that being there. I actually have read the POH. Amazing how rapidly I forget things. Thanks again.
In reply to:
do not allow the airplane to remain in uncoordinated flight for periods in excess of 30 seconds…
And there lies the rub with searching an electronic version of the POH for “slip” (whole word only): I missed “slips” and “uncoordinated flight”.
Lousy technology! [;)]
Mike.