# Airworthiness Directives; The Boeing Company Airplanes
> **Rule** · Final rule. · Published 2020-12-10 · Effective 2021-01-14 · 85 FR 79413
## Document
- **Document number:** 2020-27006
- **Category:** airworthiness
- **Manufacturer:** The Boeing Company
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 85 FR 79413
- **Publication date:** 2020-12-10
- **Effective date:** 2021-01-14
- **FAA docket:** Docket No. FAA-2020-0573
## Abstract

The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. This AD was prompted by a determination that the upper wing skin at engine nacelle points may be subject to undetected cracking. This AD requires repetitive ultrasonic inspections of the upper wing skin at certain engine strut positions for cracking; repetitive detailed and ultrasonic inspections of the strut lower spar fitting, diagonal brace strut end clevis, and diagonal brace wing attach end clevis for cracking; repetitive detailed inspections of lower link fitting at certain engine strut positions for cracking; and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2020/12/10/2020-27006/airworthiness-directives-the-boeing-company-airplanes)
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