Flight Controls; Elevator Control Horn

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FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Flight Controls; Elevator Control Horn SAIB: CE-13-23 Date: March 21, 2013 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) advises owners and operators of Univair Aircraft Corporation Ercoupe Models 415-C, 415-CD, 415-D, or other Ercoupe model airplanes with a continuous trailing edge elevator of an airworthiness concern regarding the elevator control horn and elevator attachment.

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

Background

The Federal Aviation Administration (FAA) received a field report of a loose elevator horn on an Ercoupe 415-C during restoration of the airplane. Although the external appearance of the elevator was unremarkable, teardown of the elevator revealed the elevator horn attach bracket had only one secure fastener out of four as a result of severe corrosion where the steel elevator control horn attached to the aluminum lateral stiffener. Investigation indicated dissimilar metals (steel attached to aluminum), and the corrosion prevention means of this vintage, were the primary cause of the corrosion. Similar undetected corrosion could occur on other airplanes of this type featuring elevators with a continuous (compared to the split-type) trailing edge.

Later model Ercoupe series airplanes using an aluminum (not steel) elevator control horn in conjunction with the split-type trailing edge are not subject to this SAIB.

As originally designed, this area of the elevator has no adequate means of internal inspection. Univair Aircraft Corporation has issued Service Bulletin No. 34, dated January 4, 2013, to address this limitation and minimize the potential of corrosion going undetected before it exceeds 25 percent of the cross sectional area. The service bulletin adds two round holes (aft of the aluminum elevator stiffener) and one trapezoidal hole (forward of the stiffener) to provide inspection access through the lower elevator skin.

Recommendations

The FAA recommends that all owners and operators of the Univair airplanes identified in the introduction of this SAIB comply with Univair Aircraft Corporation Service Bulletin No. 34, dated January 4, 2013. If corrosion is found upon compliance with this service bulletin or during subsequent inspections, we recommend you report it to the FAA contact identified below. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection contained in this SAIB, and assigned OMB Control Number 2120-0731.

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Richard Thomas, Aerospace Engineer, Mechanical Systems, ANM-100D, FAA, Denver Aircraft Certification Office, 26805 E. 68th Ave., Suite 214, Denver, Colorado, 80249-6339; phone: (303) 342-1085; fax: (303) 342-1088; email: [email protected].

For Related Service Information Contact

Univair Aircraft Corporation, 2500 Himalaya Road, Aurora, Colorado 80011-8156; phone: (888) 433-5433; fax (800) 457-7811; email: [email protected]; website: http://univairparts.com.