# Airworthiness Directives; McDonnell Douglas Model DC-8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, DC-8-43, DC-8-51, DC-8-52, DC-8-53, DC-8-55, DC-8-61, DC-8-61F, DC-8-62, DC-8-62F, DC-8-63, DC-8-63F, DC-8F-54, and DC-8F-55 Series Airplanes
> **Rule** · Final rule; request for comments. · Published 2001-03-06 · Effective 2001-03-21 · 66 FR 13414
## Document
- **Document number:** 01-4933
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 66 FR 13414
- **Publication date:** 2001-03-06
- **Effective date:** 2001-03-21
- **FAA docket:** Docket No. 2001-NM-26-AD
## Abstract

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-8-31, DC-8-32, DC- 8-33, DC-8-41, DC-8-42, DC-8-43, DC-8-51, DC-8-52, DC-8-53, DC-8-55, DC-8-61, DC-8-61F, DC-8-62, DC-8-62F, DC-8-63, DC-8-63F, DC-8F-54, and DC-8F-55 series airplanes. This action requires modification of the flow control system by rerouting the bleed air ducts to warm the pitot tube lines. This action is necessary to prevent the pitot lines from freezing, which could result in erroneous or total loss of airspeed indications to the flight crew, and consequent loss of control of the airplane. This action is intended to address the identified unsafe condition.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2001/03/06/01-4933/airworthiness-directives-mcdonnell-douglas-model-dc-8-31-dc-8-32-dc-8-33-dc-8-41-dc-8-42-dc-8-43)
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