The Wichita plane maker has developed a supplemental inspection program designed to stem concerns of possible corrosion and fatigue stress on its fleet of nearly 145,000 100- and 200-series single-engine aircraft produced between 1946 and 1986. The inspections are being added to service manuals for 200-series aircraft this month and for 100-series aircraft in April, the airframer says.
Compliance deadlines for the inspection program will be two years after the programs are release–December 2013 for the 200 series, and June 2014 for the 100 series.
“The supplemental inspection program we’ve developed is primarily a visual process aimed at supporting the continued airworthiness of aging airframes,” says Beth Gamble, Cessna’s principal engineer for airframe structures. “Corrosion and fatigue are inevitable, but with early detection and proper maintenance, severity and effects can be minimized.”
Cessna says the inspection program was reviewed by a customer focus group, and its members “all agree that the inspections are appropriate and necessary.”
The company notes the average age of the affected fleet is 42 years old, and that the aircraft were produced under the former Civil Aviation Regulations (CAR) Part 3 – the predecessor to the current Part 23 of the Federal Aviation Regulations. CAR did not have life-limited strength requirements nor targeted inspections for metal fatigue, Cessna notes.
Corrosion has been found in the cabin interiors and main landing gear of all models of the 100 and 200 series, Cessna says. In addition, corrosion has been found in the cantilever carry thru and cantilever wing attachments on Models 177 and 210, as well as on aircraft with strut-based wing spars.
Further fatigue cracking has been found on the horizontal stabilizer front spars of 200 series, particularly in aircraft with 9,500 + hr. Fatigue cracking also has been discovered on the vertical stabilizer attach fittings on the 150/152 aircraft, which are used for training and aerobatic moves. Fatigue cracking has been an issue in the forward door post at strut attachments on a number of models and in the rudder bar assembly on all the models.
The inspections vary by model, aircraft age and hours of operation, Cessna says, but adds the program was developed to coincide with the annual inspection. For a low-time, well-maintained aircraft, the inspections can take less than 10 hr. The program can entail 15-20 visual inspections using a borescope and/or magnifying glass. The program also encompasses five inspections that are based on existing service bulletins.
But more invasive nondestructive inspections are required when corrosion is found, cracks are suspected or for high-time airplanes (12,000+ hr.) and cases of severe usage (with 6,000+ hr.).
“The new inspection requirements we’ve developed are very simple, and are based on visual inspection that can be done quickly by a trained inspector during an annual inspection,” Gamble says. Cessna has provided training and specific inspection equipment to its authorized service providers. Cessna launched an education initiative to explain the inspections to operators. This includes an interactive presentation and short video on Cessna’s YouTube channel. “Through this education effort, we hope to answer most questions before we release the revised service manuals, Gamble says. “We encourage owners to check in with their local Cessna service affiliate at the appropriate times to have the mandatory inspections completed.”
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