Owner Organizations Collecting Usage Data

Several owner groups have joined forces to create a new web site, http://twin.cessna.org, to collect usage data for Cessna 300- and 400-series piston twins. The FAA wants this data in order to assess the impact of its proposed Airworthiness Directives that would mandate the installation of a very costly spar strap modification on these aircraft, while the owner groups are hoping that the data will help make the case for substantially relaxing the compliance times that the FAA has proposed (as low as 5,500 hours for some affected models. 

Hosted by the Cessna Pilots Association and co-sponsored by the Cessna Twins Spar Corp, the Twin Cessna Flyer, the Aircraft Owners and Pilots Association (AOPA) and the Regional Air Cargo Carriers Association (RACCA) with encouragement from the FAA, the new web site has been created to collect accurate fleet usage data from owners and operators of twin Cessnas, and to build a realistic picture of how twin Cessna aircraft are flown today. The site also contains an extensive library of information about the FAA's proposed rulemaking action, and an open forum where owners and other interested parties can ask questions and exchange ideas.

"Metal fatigue is cumulative in aluminum structures such as the wing spar, and is exquisitely sensitive to actual flight usage patterns," said John Frank, executive director of the Cessna Pilots Association. "We are concerned that the operational assumptions used by Cessna Aircraft Company and the FAA to establish the compliance times in the proposed ADs may have been unrealistically pessimistic, and we hope that the operator-furnished data we are collecting will show that the compliance times for the proposed wing spar ADs can be extended, perhaps substantially. The FAA and Cessna presented information at a meeting held in Washington D.C. on March 3 and 4, 2004, supporting the need for a spar strap modification for Cessna 401, 402, 411 and 414A models, and suggesting that similar ADs might soon be in the works for additional Cessna 300- and 400-series models..

"The safe fatigue life of these wing spars is very dependent on how the plane has been loaded and flown over its life," said Bob Vila, president of the Cessna Twins Spar Corp. "The load and flight profile assumptions used by Cessna in developing their fatigue life calculations reflect Cessna 402 aircraft used for sightseeing and Part 135 charter operations that have very heavy cabin loads and very severe duty cycles compared to the life of a typical Part 91 airplane flown for personal use."

According to Twin Cessna Flyer president Larry Ball, "It's vitally important that all owners and operators of all of twin Cessna aircraft visit this site to record their actual aircraft history and operational usage patterns. We believe that the collection of this data will help the FAA to determine that twin Cessna aircraft have lived a much kinder life than the severe usage patterns than Cessna and the FAA currently use to model the entire fleet."

Once collected, this fleet usage data will be used to develop fatigue life models that may ultimately lead to the extension of the compliance times for the aircraft currently affected by the proposed ADs and lead to a better understanding of how the entire fleet of 300 and 400 series are flown.  These results will be presented at the FAA's follow-on public meeting about the proposed ADs expected to take place sometime this summer. The Cessna Pilots Association plans to use the survey data to develop a recommended implementation plan intended to minimize the impact on owners, and the Cessna Twins Spar Corp. plans to combine the survey data with its engineering efforts to collect actual in-flight test data.
 
The sponsoring owner organizations are also concerned that many owners and operators of Cessna 300- and 400-series airplanes are still not aware of the enormous impact that the proposed ADs would have on their aircraft. Consequently, the new web site at http://twin.cessna.org is designed to be a definitive  resource where twin Cessna owners and operators can obtain all of the latest information relevant to the proposed wing spar ADs and can ask questions and conduct relevant discussion with industry experts and fellow owners/operators. 

FMI: http://twin.cessna.org