# Airworthiness Directives; McDonnell Douglas Model DC-9-14, DC-9-15, and DC-9-15F Airplanes; and McDonnell Douglas Model DC-9-20, DC-9-30, DC-9-40, and DC-9-50 Series Airplanes
> **Rule** · Final rule. · Published 2005-09-16 · Effective 2005-10-21 · 70 FR 54616
## Document
- **Document number:** 05-18314
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 70 FR 54616
- **Publication date:** 2005-09-16
- **Effective date:** 2005-10-21
- **FAA docket:** Docket No. FAA-2005-21140
## Abstract

The FAA is adopting a new airworthiness directive (AD) for all transport category airplanes listed above. This AD requires repetitive inspections for cracks of the main landing gear (MLG) shock strut cylinder, and related investigative and corrective actions if necessary. This AD results from two reports of a collapsed MLG and a report of cracks in two MLG cylinders. We are issuing this AD to detect and correct fatigue cracks in the shock strut cylinder of the MLG, which could result in a collapsed MLG during takeoff or landing, and possible reduced structural integrity of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2005/09/16/05-18314/airworthiness-directives-mcdonnell-douglas-model-dc-9-14-dc-9-15-and-dc-9-15f-airplanes-and)
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