By Steve Ells

Applies to 499 PA-28-181, PA-28-181 Piper Pilot 100i, ,PA-28R-201 Arrow III, PA-34-220T Seneca

V and PA-44-180 models that were built during or after the 2018 model year.

Piper Service Bulletin SB 1413 provides additional instructions for performance of the

inspection. SB 1413 also includes corrosion inspection information at the aft; and possibly the

forward wing spar attachment fittings.

AD 2024-10-04 requires a one-time inspection of the left and right aft wing spar attachment fittings and

the left and right aft fuselage wing spar fittings to determine if the hole in one or both of these parts

was double drilled.

This discrepancy was discovered after an unscheduled inspection following a ground collision with an


Most often, airworthiness directives (AD) are published following the issuance of a Notification of

Proposed Rulemaking (NPRM), however due to the seriousness of this issue, in this instance the NPRM

process was bypassed.

The Agency used the “direct to final rule” process due to concerns about the structural integrity of the

affected aircraft and airworthiness. However, the Agency is seeking any written data, views, or

arguments about this final rule. These comments must be received by the Agency before July 8, 2024.

Double-drilled holes of the rear wing spar attachment fittings reduces its strength below its load limit

which can lead to possible failure of the fitting, and in some cases a separation of the wing.

This AD inspection must be conducted before further flight after the effective date of the AD, which is

June 6, 2024.

Piper SB 1413 grounds affected aircraft; provides Inspection Details

SB 1413 is an 8-page document that includes the details needed to comply with AD 2024-10-04 in the

bulletin. Part I of the bulletin grounds all affected aircraft after June 6, 2024. Operators are permitted

one flight to a repair facility. The flight must be at speeds at or below Va, must be flown with minimum

crew, may include fuel stops and may not be longer than 10 hours of operation.

Part II calls for removal of the bolts and nuts in the wing-to-fuselage joint. The holes are measured to

determine that they aren’t over-sized and are round. If the holes are in compliance with the size

measurement and are round, the requirements of the AD are complete. Secure the aft spar attachment

by installing the bolt and washers that were removed in step 2. Install a new nut, and torque 360–390

in-lb. Make a logbook entry documenting compliance with this service bulletin, including a statement

describing the results of this inspection.


The AD says that the corrosion inspection portion of SB 1413 (Part II) is not directly related to the unsafe

condition of the AD so is NOT part of the required actions of the AD.

However, due to the high potential for corrosion and the fact that access is open, I suggest that owners

conduct a full corrosion inspection of both the front and rear spar attachment fittings.

The Corrosion Inspection, removal, thickness determination, and repair schemes

The AD points out that the rear (and forward) wing spar assemblies consist of steel fittings riveted to

aluminum structure and that these metals are subject to dissimilar metal corrosion.

Carefully inspect these areas for irregularities such as blisters, flakes, chips, lumps, bulging skins and

missing rivets. If corrosion is found, remove corrosion in accordance with FAA Advisory Circular AC

43.13-1B, Chapter 6.

After corrosion removal utilize direct inspection methods, or if that’s impossible use non-destructive

methods including ultrasound, eddy current, or equivalent, provided that such method achieves a

measurement accuracy of ± 0.005 inches or better to determine the thickness of the aft spar (0.61) and

the stiffener (0.0225) metal.

If the thickness is below these minimums, obtain and install Aft Spare Attachment Replacement Parts.

The part number for Aft Spar plates (installed on the wings) of all models affected by the AD is 66762-

000. The part number for LH aft spar fitting (installed on fuselage) is 62448-002 except for the Seneca V

which is 68621-002. The part numbers for the RH aft spar fitting (fuselage) is 62448-003 except for the

Seneca which is 68621-003.

Report any rework to Piper electronically by completing and submitting the Inspection Feedback Form at

Make a logbook entry documenting compliance with this service bulletin, including a statement

describing the results of this inspection and any rework that was performed.