Piper has issued Service Letter (SL) 1327A, which supersedes SL 1327 in its entirety. 

Reason for Revision 

To correct the list of affected aircraft serial numbers and to provide instructions for a modification to facilitate required recurring inspections. 


Cracks may be discovered in the doublers (aka wing skin pan) that reinforce the wing skin, localized around the wing walkway. Aircraft with this condition are considered airworthy and may continue to operate, provided that a recurring inspection is performed on the affected wing skin. However, cracks may appear in areas normally obscured by the wing walkway material. This service letter provides a modification to the wing walkway by removing and replacing part of the wing walkway material to facilitate the required recurring inspection. 

The service letter consists of three parts: 

  • Part I. Initial Inspection 
  • Part II. Recurring Inspection 
  • Part III. Modification  

Compliance Time 

Initial compliance with Part I is to coincide with the next regularly scheduled maintenance event, but not to exceed the next 50 hours time in service. Thereafter, recurring compliance with Part II is required at an interval of 50 hours time in service. Compliance with Part III is required upon discovery of cracks in the wing skin pan. 

The service letter is effective on September 19, 2023. 

To download PDF of complete service letter, click here.