Cessna parent company Textron Aviation issues Service Bulletin MEL-57-04 on June 30, 2020 warning of cracks found in the front spar upper cap. Cracks in this area could cause the spar cap to break resulting in flight instability and potentially loss of control.
The bulletin lists inspection of the spar cap as mandatory for aircraft with 18,000 hours and subsequent inspections each 1,000 hours thereafter. The inspection instructions involve a visual inspection of the area. If no cracks are seen but the area is suspect, an eddy current inspection should be performed.
Aircraft that are found to have cracks must be immediately grounded and the mechanic is instructed to contact Textron Aviation Team Structures. Regardless of results an inspection results form must be completed and returned to Textron.