This week, we discuss what you should know about two mandatory service bulletins that affect the Cessna 210 and Cessna 177 Cardinal. If you either own or in the market either of these airplanes, you won’t want to miss this!
What is one major design feature of the Cessna Cardinal and most 210’s that set it apart from all other Cessna singles? If you said the elimination of the wing strut, you’d be right. Now we’re not going to get into all of the features and benefits of these airplanes as we’ve already covered them in detail in past episodes. However, in a nutshell, the absence of a wing strut means that the wing structure found in these airplanes must be much beefier than those found in say a Cessna 182. That’s because the wing spar itself must withstand a lot more aerodynamic load and stress that would otherwise be absorbed by the strut. This sort of wing design is known as a cantilever wing, where the carry-thru spar, ribs, and stringer take the stress.
You may recall that certification standards for airplanes with a standard airworthiness certificate in the normal category are required to withstand loads of +3.8 g and -1.52g, meaning the wings must be able to withstand loads 3.8 times the weight of the airplane before structural failure occurs. Unfortunately, that wasn’t the case for a Cessna 210 that broke apart in flight back in May of this year. The cause of the accident was found to be fatigue cracking in the carry-thru spar.
As a result, Textron Aviation issued a mandatory service bulletin SE-57-06 for the Cessna 210G thru T210R –the cantilever Cessna 210s, as well as SE-57-07 for all Cessna 177 Cardinals. According to Cessna, the reason for the mandatory service bulletin is because the carry-thru spar can develop corrosion and cracks. A crack in the carry-thru spar can develop to a point that the carry-thru spar can have structural failure that can result in the subsequent loss of the airplane and/or wing separation. Non-compliance with this service letter may result in undetected cracks. The service letter provides instructions to do a detailed visual inspection and an eddy-current inspection of the lower surface of the carry-thru spar.
So my friends, it’s obvious that this service letter should be taken quite seriously. Now I’m not going to get into all the details of how the detailed inspection and eddy-current inspection needs to be done as it needs to be done by an A&P and a properly qualified technician trained in conducting non-destructive testing.
If you own either a 210 or Cardinal, I strongly suggest complying with this service letter as soon as possible. According to SE-57-06, 210 models with more than 1,500 hours TTAF should comply within 10 flight hours, depending on utilization. As for Cardinals, SE-57-07 suggests compliance should also occur within 10 flight hours if AFTT is greater than 2,500 hours, depending on utilization. By the way, by utilization, each service letter categorizes utilization as either extreme or typical, which we’ll go into more detail on shortly.
There’s also a stipulation that indicates the Carry-Thru spar inspection presented in this service letter applies to airplanes listed in the Effectivity Section. The compliance time is for unmodified
airplanes, and represents the maximum allowable time. Airplanes that have been modified to alter the airplane design, gross weight, or airplane performance, may need to inspect sooner. Examples of common supplemental type certificates(STC’s) include vortex generators, wing cuffs, STOL kits, wing tips, and add-on wing fuel tanks. In other words, compliance may vary for aircraft that have been altered or modified. You should contact the STC holder for revised inspection intervals.
For those of you in the market for a Cessna Cardinal or 210, bear in mind that despite this service letter having the title of Mandatory, compliance is actually optional for Part 91 operators. In other words, owners of affected aircraft do not have to comply with this service letter in any way, shape or form. That’s because at the time of this recording, this service letter is not part of an airworthiness directive. Thus, I strongly suggest that this service letter be complied with during the prebuy phase unless there’s a logbook entry stating that compliance has already be done along with the results and ideally a workorder from the shop that performed the work detailing everything.
Now I’m not telling you all this to scare you away from these airplanes. I estimate that most aircraft in service today in typical utilization environments are just fine. It’s just a matter of responsible due diligence to ensure you’re getting a safe and reliable airplane.
According to a July 2019 AOPA article, the FAA has issued an Airworthiness Concern Sheet to request information from operators of affected airplanes to help the FAA determine the status of the fleet—including total time-in-service on airframes, any modifications or supplemental type certificates, and the usage environment in which aircraft are operated. I would encourage all owners and operators of these aircraft to submit comments to the FAA or AOPA following compliance of the service letter.