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U.S. Department of Transportation
Federal Aviation Administration Airworthiness Concern Sheet Date: April 2, 2026
Reply to:
Name: Nikholas Brito-Ross Title: Aviation Safety Engineer Office: East Certification Branch Street Address: 107 Charles W. Grant Pkwy City, State, ZIP: Hapeville, GA 30354 Telephone: 404-474-5528 Electronic Mail: ECB-COS@faa.gov Make: Piper Aircraft, Inc. (Piper) Model / Series: PA-28, PA-32, PA-34, and PA-44, specifically those called out in SAIB AIR-21-10 Serial Numbers: All Serial Numbers Reason for Airworthiness Concern: Forward Wing Spar Attachment Corrosion Federal Aviation Administration (FAA) Description of Airworthiness Concern The FAA recently received a report of severe corrosion on the left-hand forward wing spar attachment, specifically the forward spar through to the forward fuselage attachment fitting and on the rivet heads of said attachment, on a Piper PA-28-161 (Figures 1&2). Further inspection of that fleet located four more airplanes with corrosion, although less severe than the aforementioned airplane. The corrosion was found during a general visual inspection of the area; but, to conduct a full evaluation, disassembly of the area was necessary. The corrosion was found by following the recommended inspection discussed in Special Airworthiness Information Bulletin (SAIB) AIR-21-10 (attached below). It has been found that accessing the location discussed in the SAIB is difficult, and the full extent of corrosion, if present, may not be apparent without disassembly.
Request for Information The FAA is interested in receiving information on any other discoveries of corrosion on the forward wing spars, attachment fittings, and rivets of PA-28, PA-32, PA-34, and PA-44 airplanes.
Piper has released Service Bulletin (SB) No. 1400A, dated March 13, 2026, and is available at www.piper.com/technicalpublications/. The subject of Piper SB No. 1400A is “Forward Wing Spar-To-Fuselage Attach Fitting Corrosion Inspection” and it affects the same models as this Airworthiness Concern Sheet. This SB provides inspection, removal, and replacement instructions for the involved areas.
We recommend operators inspect this area, as detailed in Piper SB No. 1400A, and we request they provide information, including a description of any corrosion found, environment of regular operation and storage, available photos, airplane serial number, and time in service. Additionally, the FAA is interested in receiving feedback on any difficulty completing the inspection instructions in Piper SB No. 1400A.
Please provide any other information you feel may be helpful for us to consider as part of our evaluation.
This Airworthiness Concern Sheet (ACS) is intended as a means for FAA Aviation Safety Engineers to coordinate airworthiness concerns with aircraft owners/operators through associations and type clubs. At this time, the FAA has not made a determinati on on what type of corrective action (if any) should be taken. The resolution of this airworthiness concern could involve Airworthiness Directive (AD) action or a Special Airworthiness Information Bulletin (SAIB), or the FAA could determine that no action is needed at this time. The FAA’s final determination will depend in part on the information received in response to this ACS.
The FAA endorses dissemination of this technical information to all manufacturers and requests association and type club comments.
Attachments:
Service Difficulty Report Accident/Incident Data System Service Letter / Bulletin Special Airworthiness Information Bulletin Federal Aviation Administration or National Transportation Safety Board Safety Recommendation Airworthiness Directive Alternate Means of Compliance Risk Analysis Transmittal:
Federal Aviation Administration Airplane Owners and Pilots Association Experimental Aircraft Association Type Club Type Certificate Holder Other:
Response Requested By:
Emergency (10 days) Alert (30 days) Information (90 days)
Figure 1: Forward Spar, Attachment Fitting, and Rivets with Corrosion from a PA-28-161.
Figure 2: Attachment Fitting (top) and Forward Spar (bottom) from a PA-28-161.
FAA Aviation Safety
SPECIAL AIRWORTHINESS
INFORMATION BULLETIN
SUBJ: Wing, Attach Fittings (JASC 5740) This is information only. Recommendations aren’t mandatory.
SAIB: AIR-21-10 Date: June 29, 2021 Introduction This Special Airworthiness Information Bulletin is to advise owners and operators of Piper Aircraft, Inc. PA-28, PA-32, PA-34, and PA-44 (see list of specific models in “Background” section) airplanes of the potential for corrosion of the forward spar to fuselage attach fittings, in an area that may not be easily accessible for inspection
We have determined that no regulatory action is necessary at this time because the airworthiness concern is not an unsafe condition that would warrant an FAA AD under 14 CFR part 39.
Background Piper Aircraft, Inc. issued Service Bulletins (SB) 789A, 977, and 1244B to inspect for corrosion on the aft wing spar to fuselage attach fittings. At the time the service bulletins were written, the corrosion was attributed to water intrusion, and forward attach fittings were not considered to be subject to the water intrusion issues affecting the aft attach fittings. Therefore, inspections of the forward attach fittings were not included in those service bulletins.
Since then, the FAA became aware of several cases of severe corrosion on the forward attach fittings from operators in Florida. While no evidence exists of water intrusion at the forward locations, the potential exists for galvanic corrosion between the dissimilar metals of the steel fittings and aluminum spar. Due to the restricted accessibility of the forward attach fittings in some airplanes, owners may be neglecting to have this area inspected. See Figures 1 through 3 depicting corrosion location and characteristics.
The specific Piper Aircraft, Inc. models affected are: PA-28-140, PA-28-150, PA-28-151, PA-28- 160, PA-28-161, PA-28-180, PA-28-181, PA-28-201T, PA-28-235, PA-28-236, PA-28R-180, PA- 28R-200, PA-28R-201, PA-28R-201T, PA-28RT-201, PA-28RT-201T, PA-28S-160, PA-28S-180, PA-32-260, PA-32-300, PA-32-301, PA-32-301FT, PA-32-301T, PA-32-301XTC, PA-32R-300;
PA-32R-301 (HP), PA-32R-301 (SP), PA-32R-301T, PA-32RT-300, PA-32RT-300T, PA-32S-300, PA-34-200, PA-34-200T, PA-34-220T, PA-44-180, and PA-44-180T.
Recommendations The FAA is recommending that owners take special care to ensure that the forward wing attach fittings are visually inspected during annual or 100-hour inspections in accordance with the applicable Piper Aircraft, Inc. Maintenance Manual. Some operators have had inspection panels or borescope inspection holes installed to facilitate inspection (contact Piper Aircraft, Inc. for acceptable options). “Powdery” rivets in the attach fitting are indicative of corrosion between the
steel and aluminum surfaces. Particularly susceptible are those airplanes operating in coastal or otherwise corrosive environments.
For Further Information Contact Dan McCully, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5548; fax: (404) 474-5605; email:
william.mccully@faa.gov.
35630 38643 T0I
SKETCH A
SECTION A-A BOLT NAS1104-17 WASHER AN960-416L (UNDER HEAD) WASHER AN960-416 (UNDER NUT) NUT MS21045-4 SEE NOTE
0.12 MIN.
0.35 MAX.
•
• TORQUE NUT 50-60 IN-LBS
•
• NOTE OR AN960-416L AS
REQUIRED TO LEAVE A MAXIMUM OF 1 1/2
THREADS OR MINIMUM
OF BOLT CHAMFER
EXPOSED Figure 1. Forward Attach Fitting
Figure 2. PA-28 Corroded Forward Attach Fitting and Spar Section (removed)
FORWARD FITTING INSIDE
WING LEADING EDGE
SHOWING CORRODED RIVET HEADS
Figure 3. Wing Interior Showing Galvanic Corrosion
Service documents this concern sheet cites · 1
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