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ACRO E-mail Archive Thread: [IAC-L:135] RE: Pitts AD on-line

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ACRO E-mail Archive Thread: [IAC-L:135] RE: Pitts AD on-line


Thread: [IAC-L:135] RE: Pitts AD on-line

Message: [IAC-L:135] RE: Pitts AD on-line

Follow-Up To: ACRO Email list (for List Members only)

From: "Dave Swartz" <dswartz at>

Date: Fri, 20 Jun 1997 07:46:00 UTC


> From: Ronald Saglimbene <6Sags at>
> To: Multiple recipients of list <iac-l at>
> Subject: [IAC-L:130] RE: Pitts AD on-line
> Date: Thursday, June 19, 1997 7:03 PM
> Regarding the new NPRM on the longeron AD for Pitts aircraft:
> A  review of the original AD states: "Upon investigation of the 
> incidents, further analysis and testing show that hard landings and 
> snap roll maneuvers in excess of the +6 and -3 gravity (``g'') force 
> limits cause enough stress and fatigue to crack the upper longerons. 
> This condition, if not corrected, could result in failure of the 
> airframe and possible loss of control of the airplane."
> Based upon this, if a placard is to be put in the airplane, it should
> "No positive snap rolls above 160 mph" which is about how fast you have 
> to be going in a Pitts in order to generate +6gs in a snap.
> It would be nice if the FAA would read it's own material before issuing
> a restrictive amendment .
> Ron Saglimbene   

A close approximation to G's imposed by a snap can be calculated by
dividing the entry speed by the stall speed and squaring the result.  For
an S2B (maximum approved positive snap speed 140) ---    (140/61)**2 =
Snapping at 160 would result in (160/61)**2 = 6.88 G's  

Dave Swartz
Plantation Florida


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