I hate to write another aging aircraft article, but this one includes information from Cessna with actual teeth. In a effort to ensure safety of flight, Cessna generates Supplemental Inspection Documents (SID) which are added to the Service Manuals of the affected airplane models. These documents detail additional inspections, checks, and servicing that Cessna has determined need to be performed. The initial times and reoccurring times are established in the SID as well. Most are simple visual inspections, but others require specially approved Non-destructive Testing (NDT) methods and can be pretty expensive. The Twin Cessna owners are probably familiar with the idea of SIDs, but the single engine crowd has been spared the trouble….. until now.
The new SID are added to the Service Manuals as a new section, Section 2A. For the US registered airplanes these new inspections are not required by the FAA. In most other countries these will be required in a similar way that manufacturer service bulletins are required. However, just because you have a US registered plane doesn’t mean you shouldn’t investigate each of these documents.
Cessna has released revised Service Manuals for the 200 series legacy models with the new Section 2A. The 100 series are soon to follow with similar updates.
Paragraph 2 Inspection Requirement
This paragraph defines two different inspection time intervals based on how the aircraft has been operated. Severe usage is defined as average flight length of 30 minutes or low altitude operations for more than 30% of the airplanes life. This is an incredibly frustrating criteria for general aviation aircraft owners because there is no requirement for documentation of previous operation. The current owner is left to his/her own devices to determine the historical usage of the plane. The premise of adjusting inspection intervals based on usage and environment is a good one, just difficult to implement on the typical general aviation airplane.
The interesting part of the usage and environmental decision is that all of the legacy planes are at least 25 years old and the longest initial inspection interval is 20 years. By this accounting all legacy airplanes are already past due for the SID. Cessna addresses this problem in SID 2A-13-00 page 5, paragraph 7C, where completion of all initial inspections is extended to December 31, 2013. While this creates a certain level of urgency, it also illuminates the need to figure out the initial due times.
2A-13-00 page 1 paragraph 1.A.(4) makes a statement not seen before in the legacy aircraft servicing information. “The Supplemental Structural Inspection Program is valid for model 210 airplanes with less than 30,000 flight hours. Beyond this, continued airworthiness of the airplane can no longer be assured. Retirement of this airframe is recommended when 30,000 flight hours has been accumulated.”
An ultimate life limit is a concept not familiar to legacy Cessna owners. There aren’t very many 210s that have made it to 30K flight hours. For those in the States, this limit is a recommendation just as it is stated. For those in other countries, it will be up to those governing bodies to make the call as to the whether this “recommendation” is required or not.
Cessna’s list of supplemental inspections touch on most of the known aging aircraft issues on the 200 series airframes. Generally, the inspections are appropriate to the specific issue and are a good measure of the structure’s condition. The following is a paraphrased list of the supplemental inspections and is not to be considered a complete or exhaustive description:
27-20-01 Rudder Pedal Torque Tube Inspection: Visual inspection of the rudder pedal torque tube attachment arms and welds for cracks, corrosion, or signs of fatigue.
27-30-02 Elevator Trim Pulley Bracket and Actuator Bracket Structure Inspection: Visual inspection of structure surrounding the trim pulley bracket and actuator bracket for corrosion, cracks, deformation, and installation of service kit SK210-139.
32-10-01 Main Landing Gear Retraction System Inspection: Visual inspection to verify completion of SEB01-2 on the main gear actuators.
32-13-01 Landing Gear Spring Corrosion Inspection: Visual inspection to ensure corrosion protection is in place on the gear legs.
32-20-1 Nose Gear Torque Link and Fork Inspection: Visual inspection for damaged or worn hardware and condition of torque links.
32-20-2 Nose Gear Lower Trunnion Inspection: Visual and Eddy Current inspection of nose gear lower trunnion if SEB94-19 has not been completed.
53-11-1 Carry-Thru Spar Corrosion Inspection: Visual inspection of the wing spar carry-thru for corrosion.
53-11-2 Carry-Thru Spar Inspection: Visual and Eddy Current inspection of wing attachment lugs and root rib attachments.
53-12-02 Firewall Inspection: Visual inspection of the firewall exhaust hanger hanger brackets and supports. Also installation of SE79-34.
53-30-01 Cabin Interior Skin Panels Corrosion Inspection: Remove cabin sound dampening material and visually inspect surrounding structure for corrosion.
53-47-01 Seat Rails and Seat Rail Structure Corrosion Inspection: Visual inspection of seat rails for corrosion and compliance with AD 2011-10-09.
55-10-1 Horizontal Stabilizer, Elevator and Attachments Inspection: Visual and Eddy Current inspection of horizontal tail feathers, their attachments and surrounding structure. This requires removal of all the tail feathers to complete.
55-10-2 Elevator and Trim Tab Inspection: Visual inspection of foam filled elevator trailing edges and foam filled trim tab.
55-30-01 Vertical Stabilizer, Rudder and Attachments Inspection: Visual and Eddy Current inspection of vertical tail feathers, their attachments and surrounding structure. This requires removal of the vertical fin and rudder to complete.
57-11-1 Wing Structure Inspection: Visual and borescope inspection of the complete interior wing structure for cracks, working rivets, and working Hi-Shear fasteners.
57-11-2 Wing Structure Corrosion Inspection: Visual and borescope inspection of the complete interior wing structure for corrosion.
57-12-01 Wing Root Rib Corrosion Inspection: Visual and borescope inspection of wing interior for corrosion.
57-30-01 Wing Front Spar Inspection: Visual and Eddy Current inspection of front spar attachment area and replacement of hardware.
57-51-01 Aileron Support Structure Inspection: Visual and Eddy Current inspection of the aileron hinges, hardware, and pushrods for damage and wear.
57-53-01 Flap Tracks Corrosion Inspection: Visual inspection of flap tracks for exfoliation corrosion.
71-20-01 Engine Mount Inspection: Visual inspection of the engine mount tunnel structure for structural integrity.
Section 2A of the Service Manual also includes a section on inspection criteria for control cables. There’s not a lot of new information here on inspecting control cables. It also doesn’t give a specific time table for the inspection. What it does do is ensure inspectors fully understand the make up of cable systems and the importance of detailed inspections.
Keep in mind, it is very likely that the flight control cables in your airplane are original factory installed units. That means they are at least 25 years old and could be as much as 65 years old. I can’t imagine anyone would argue against a little special attention to these very important items during routine inspections..
Corrosion Prevention and Control Program
The initial CPCP inspection is expected to be performed in conjunction with the first SID inspection. This is a very extensive section and an indepth discussion is beyond the scope of this article. In other words, we’ll talk about it in a future CPA magazine issue.
The SID also includes forms and a system to report the findings of these inspections. It is not logical to believe these machines have an infinite life span. They were never expected to last this long, so no system of long term measure was created to evaluate these airframes. It has finally come to everyone’s attention that geriatric care and tracking is essential for continued safe operation.
Thus far, Cessna has accumulated the data to generate the SID from a relatively small sample of aircraft. Reporting findings from a mass of inspections will allow refinement of the SID and give them more validity. If a large quantity of reports show no problems, then we would hope Cessna would increase the times for the inspections, thus reducing the financial burden of ownership.
I believe that more maintenance is not always better, as performing maintenance is often a cause to need more maintenance. For that same reason, I also believe that replacing parts just because they’ve reached some arbitrary time in service is rarely a proper solution unless their condition can not be monitored.
I do strongly believe that if we can monitor and quantify conditions and perform maintenance as the data supports it, we can maintain our aircraft as efficiently as is practical. Cessna has created a method to report and track findings from a fleet of data. It is to everyone’s advantage to report details of these inspections. If problems are being found, then we all want to know, with the hope that catastrophe can be avoided. Let’s keep them flying safely.