# Airworthiness Directives; CFM International CFM56-7B and -7B/2 Series Turbofan Engines
> **Rule** · Final rule; request for comments. · Published 1998-09-22 · Effective 1998-10-07 · 63 FR 50482
## Document
- **Document number:** 98-25007
- **Category:** airworthiness
- **Manufacturer:** CFM International CFM56-7B and -7B/2 Series Turbofan
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 63 FR 50482
- **Publication date:** 1998-09-22
- **Effective date:** 1998-10-07
- **FAA docket:** Docket No. 98-ANE-55-AD
## Abstract

This amendment adopts a new airworthiness directive (AD) that is applicable to CFM International CFM56-7B and -7B/2 series turbofan engines. This action requires initial and repetitive inspections of certain hydromechanical unit (HMU) overspeed governor (OSG) spool valves for out-of-specification conditions or the presence of heavy contact or galling on the spool valve, and optional installation of an improved HMU as a terminating action to the inspections. This amendment is prompted by a report of a flameout that occurred on a flight test engine due to a failed HMU OSG spool valve shaft. The actions specified in this AD are intended to prevent failure of the HMU OSG spool valve shaft, and subsequent engine flameout.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1998/09/22/98-25007/airworthiness-directives-cfm-international-cfm56-7b-and--7b2-series-turbofan-engines)
---
*AI Analytics · CC0 1.0*