FAA decides against immediate AD on turbo twin Cessna exhausts, will issue 30-day NPRM for public comment
Following quick, intense action by the Aircraft Owners and Pilots Association and the Cessna Pilots Association, the FAA has decided not to issue an “immediately adopted rule” establishing a costly exhaust system airworthiness directive on turbocharged twin Cessna models T310 to 421C (except 337).
Instead, the agency will issue a notice of proposed rulemaking (NPRM) allowing for a 30-day comment period before the AD becomes effective.
“This AD will likely be extraordinarily expensive,” said AOPA President Phil Boyer. “The FAA needs to hear from the owners and operators who have considerable experience with Cessna exhaust systems before the agency determines the final form of the AD.”
The problem is that a poorly maintained exhaust system can allow hot gases to escape and burn through engine mount beams or, in some cases, the wing spar, causing the aircraft to catch fire or break apart in flight.
The FAA told AOPA June 18 that it was about to issue a final rule AD, bypassing the informal comment period of a normal NPRM. The AD would affect some 9,400 turbocharged Cessna twins.
But it’s not a new problem. An AD was first issued in 1975 and subsequently amended. That was followed by a 1996 special airworthiness information bulletin. The latest proposed AD has been under consideration within the FAA for three years.
That’s why AOPA challenged the need to issue an immediate AD now without the usual public notice and opportunity for comment.
In a June 24 letter to FAA Administrator Jane Garvey, AOPA President Boyer noted that the Administrative Procedure Act requires the FAA to seek public comments before issuing a final rule. The agency can only bypass that requirement when the FAA finds it is in the public interest to do so; for example, when there is an immediate threat to public safety.
“It is hard for us to understand how the FAA could make such a finding when this has been a matter under consideration by the administration and others for so long,” Boyer told Garvey. “While we are appreciative of the safety issues involved, we know of no immediate and compelling event warranting this precipitous action.”
In that letter, and through personal contacts with key FAA aircraft certification officials, AOPA asked the agency to withdraw the immediate rule and issue an NPRM.
On June 25, the FAA informed AOPA that it will publish the proposed AD affecting turbocharged twin Cessna exhaust systems as NPRM 97-CE-67-AD the week of June 28. The public will have until August 9 to comment.
The FAA wants to hear from twin Cessna owners. Elizabeth Erickson, director of the FAA’s Aircraft Certification Service, told AOPA that the agency wants to know the economic impact on owners and suggestions for alternate means of compliance.
“It’s vitally important that government and industry cooperate to achieve aviation safety objectives,” said Boyer. “We appreciate the FAA’s responsiveness to our concerns on this issue.”
Complete details of the new AD won’t be available until the NPRM is published, but AOPA understands that it will require continued inspections under the existing 1975 AD (75-23-08) for the next 500 hours. That AD calls for 50-hour inspections for stainless-steel exhaust systems and 100-hour intervals for systems made entirely of Inconel. Upon the accumulation of 500 hours, the entire exhaust system aft of the slip joints must be removed and sent to one of three shops for inspection and determination as to whether it is made of stainless steel or Inconel.
Every 500 hours thereafter, the exhaust slip joints must be removed and inspected. Upon accumulation of 2,200 hours or next engine removal, the entire system aft of the slip joints must be removed again and sent to a repair station for inspection.
Boyer’s letter to Administrator Garvey and the NPRM (when published) proposing an exhaust system airworthiness directive on turbocharged Cessna twins will be available on AOPA Online.
The 350,000-member Aircraft Owners and Pilots Association is the world’s largest pilot organization. Its watch on airworthiness issues is part of AOPA’s efforts to control the cost of flying.
June 25, 1999