Cessna 177 Cardinal Carry-Thru Spar Inspection (AD 2023-02-17)
A visual and eddy current check of the carry-thru spar lower cap, required on every 177 variant.
AD 2023-02-17put the Cardinal under the same carry-thru spar inspection the FAA first required on the Cessna 210.
The trigger was the 2019 in-flight breakup of a T210M in Australia, traced to a fatigue crack that started at a corrosion pit in the spar's lower cap. The AD took effect on March 20, 2023. It covers the 177, 177A, 177B, 177RG, and F177RG, along with later 210 models.
The Cardinal's carry-thru spar is similar to the earlier Cessna 210. The upper surface is exposed, and the spar may not have left the factory with zinc chromate primer. Cardinals were not delivered with the foam pad used on later 210s. The FAA still received reports of corrosion on the lower cap. The AD points the inspection steps to Textron service letter SEL-57-09, Revision 1.
What the inspection involves
- A visual inspection of the carry-thru spar lower cap with a 10X magnifier, looking for corrosion, cracks, and damage
- An eddy current inspection of the cap's kick area and any spot where corrosion was removed
- Corrosion removal within the AD's limits, then primer and a corrosion-inhibiting compound
If your Cardinal hasn't complied yet
The AD gave owners 200 hours or 12 months, whichever came first. That window has closed. Under 14 CFR 39.7, operating an airplane that doesn't meet an applicable AD is a violation. This matters most for Cardinals coming out of storage, changing hands, or missing a clear logbook entry.
The FAA calls the AD an interim action, so more rulemaking may follow.
As of September 29, 2023, the FAA had received 547 inspection reports for 177-series airplanes under this AD. Corrosion was reported on 242 of those airplanes. 34 carry-thru spars were removed from service because of cracking, corrosion, or other damage. TheAustralian Transport Safety Bureaupublished those FAA figures. They are reports received by that date, not a result for every Cardinal. In May 2025 the FAA told the ATSB that replacement carry-thru spar structures had been approved, and that the work with Textron Aviation was still going.
What it costs
The FAA's estimates, at $85 an hour:
- Access and visual inspection: about 20 hours, $1,700
- Eddy current inspection: about $600, as a contracted service
- Total: about $2,300
- New carry-thru spar for a 177-series airplane, if one is needed: about $40,200
Who does the work
Your A&P handles access and the visual inspection. The eddy current step is specialized NDT work that most shops contract out. We connect you with an eddy current inspector who covers your airport.
Related inspections
Cessna 210 Carry-Thru Spar InspectionWing Spar Eddy Current InspectionWing Spar Corrosion Repair
This page summarizes AD 2023-02-17. Always work from the current AD text and your mechanic's judgment.
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