In this thread:
http://www.pprune.org/private-flying...rformance.html
there was some drift towards the spinning characteristics of a C172. To avoid further thread drift, I have created this new thread.
My post in the performance thread:
Quote:
The more restrictive "Utility" C of G limits for intentional spinning, are for average pilot skill. At the "normal" C of G limits a safe spin recovery is still possible, but it will probably require skills beyond that of a new pilot.
ST,
Could you expand on that? It's a long time since I read a 172 POH, so I had a quick look at one for a 1978 172N. I saw a fairly standard spin-recovery technique for spins in Utility category but nothing else.
Step Turn's Reply:
Spencer, please forgive me, I'm going to drift your thread a bit, but we'll still discuss 172's
The 172 is approved to be spun in the utility category, which category has a more restrictive C of G range than normal category. That demonstration of spin recovery (up to six turns) was made with "average pilot skill". In essence, you're not allowed to have people in the back seat for intentional spins, which seems totally reasonable to me. For this configuration, there is a POH spin procedure. There is also the expectation that you could execute a less than perfect recovery, and there is enough "room" that you're not going to exceed a limitation. (The average pilot skill thing).
The 172 (like all "normal category" certified single engine aircraft (+- the Cirrus?)) has also demonstrated compliance with the requirement that it be recoverable from a one turn spin in not more than one more additional turn - at the full C of G range. Indeed, it probably
is the spin recovery characteristics which define the aft C of G limit. However,
that requirement does not require just average pilot skill - it can be demonstrated with some practiced effort. And, the recovery could take the plane alarmingly close to a limitation or two, as long as they are not exceeded.
I can say from first hand experience, that larger Cessnas can approach Vne, and at more than 2 G recovering from the dive resulting from a one turn spin. Not territory to be fooling around in without a G meter!
So, in that way, the 172 has two different limitations, based upon how it is to be flown.
In deference to Spencer's original question, (and respect of thread drift) was you question answered to your satisfaction?
ST,
Not quite.
I've done hundreds of spins in my career, mainly in Chipmunks, but also a fair number in Citabrias, C172s and various gliders. In the case of the 172, I've done them visually and also on instruments.
As I mentioned previously, it was a long time since I had looked at a 172 handbook and I wasn't aware (or couldn't remember) the exact wording, which is subtly different from the so-called "standard" spin recovery that I was taught on Chipmunks. However, in practice, all the spins I've done in 172s, admittedly at forward C of Gs, have been non events, with the spin terminating as soon as I started easing the control column forward.
In the 1978 C172N POH that I downloaded (
http://www.tucsonaero.com/Documents/...-1978-172N.pdf), I saw the following (paraphrased and/or abbreviated):
SECTION 2: LIMITATIONS.
Normal Category (2300 lb AUW) ... Aerobatic maneuvers, including spins are not approved.
Utility Category (2000 lb AUW) ... Approved maneuvers - Chandelles, Lazy Eights, Steep Turns, Spins, Stalls (except Whip Stalls)
Looking at the load factors, Utility category allows slightly increased flaps-up G limits of +4.4, -1.76 versus +3.8, -1.52 for Normal category. Flaps down limits are the same in both cases +3.0 with no negative G allowed.
SECTION 3: EMERGENCY PROCEDURES
SPINS (inadvertant)
1. Throttle idle
2. Ailerons neutral
3. Full opposite rudder
4. Just after the rudder reaches the stop, move the control wheel briskly forward. Full down elevator may be required at aft CGs.
5. Hold the control inputs until the rotation stops.
6. As rotation stops, neutralize rudder and recover from the dive.
There is a note to say that if the pilot is disoriented, use the turn coordinator to determine the direction of rotation.
Also, there is a reference to additional information in Section 4: Normal Procedures.
This emergency spin recovery procedure, which clearly applies to both Normal and Utility category loadings, is a fairly standard spin recovery technique except that the word "briskly" is used. It is almost identical to the RAF Chipmunk Pilot's Notes spin recovery action, except for the following wording for the Chipmunk:
After a brief pause move the control column firmly and progressively forward until the spin stops.
Section 4: Normal Procedures
Intentional spins are approved within certain restricted loadings. Spins with baggage or occupied rear seats are not allowed.
Following this, there is some discussion about appropriate altitudes, height loss and spin entry, but the specified recovery technique is identical to that in the Emergency Procedures section.
ST,
Can you expand upon your previous observations, particularly since I am not allowed to experiment with spins at aft CGs? The POH implies that the same technique is valid for all gross weights and CG positions.