Wing Miscellaneous Structure

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Wing Miscellaneous Structure SAIB: CE-19-09 Date: June 10, 2019 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) informs registered owners/operators of an airworthiness concern for Mitsubishi Heavy Industries Ltd. (MHI), Models MU-2B, MU-2B-10, MU–2B–15, MU–2B–20, MU–2B–25, MU–2B–26, MU–2B–26A, MU–2B–30, MU-2B-35, MU– 2B–36, MU–2B–36A, MU–2B–40, and MU–2B–60 airplanes. Specifically, this SAIB notifies owners and operators of procedures to detect and correct cracks in the wing spacer plates, which if left uncorrected, could result in reduced structural integrity of the wings.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

As part of the MHI MU-2B aging aircraft program, one-piece and three-piece main wings were subjected to detailed teardown inspections, and cracks were found in the wing spacer plates attached to the forward lower spar area at wing station 580. It was determined that the cracks resulted from fatigue caused by flight loads.

To address this, MHI issued MU-2 Service Bulletin No. 245, dated April 21, 2016, and MU-2 Service Bulletin No. 107/57-005, dated May 3, 2016. These service bulletins describe procedures for doing a fluorescent penetrant inspection of the wing spacer plates for cracks and replacing cracked wing spacer plates with an improved part

Recommendations

The FAA recommends that owners and operators perform the fluorescent penetrant inspections detailed in the Section 1 Inspection Procedure of MU-2 Service Bulletin No. 245, dated April 21, 2016, or Service Bulletin No. 107/57-005, dated May 3, 2016, as applicable.

In the event cracks are found and subsequent maintenance is performed in the area of the wing spacer plate that allows for access to the wing spacer plate, the FAA recommends that owners and operators replace the wing spacer plates. Instructions for replacement should be performed in accordance with the Section 2 Replacement Procedure detailed in MU-2 Service Bulletin No. 245, dated April 21, 2016, or Service Bulletin No. 107/57-005, dated May 3, 2016 as applicable.

For Further Information Contact

Kristi Bradley, Aerospace Engineer, AIR-7F2, ACO Branch, FAA, 10101 Hillwood Pkwy, Fort Worth, TX 76177; phone: (817) 222-5485; email: [email protected]