# NTSB Accident CHI89MA046
> **BOEING 737-201** · 1989-01-20 · CHICAGO, IL, USA · NONE
## Event
- **NTSB number:** CHI89MA046
- **Event ID:** 20001213X27558
- **Type:** Accident
- **Date:** 1989-01-20
- **Location:** CHICAGO, IL, USA
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 33
- **Total aboard:** 33
## Aircraft
- **Make:** BOEING
- **Model:** 737-201
- **Registration:** N242US
- **FAR Part:** 121
- **Engines:** 2
- **Damage:** SUBS
## Conditions
- **Light:** DAYL
- **Weather:** VMC
## Probable cause

PREVIOUS DAMAGE TO THE AFT CONE (ENGINE MOUNTING) BOLT, WHICH RESULTED IN MISMATCHED SURFACES BETWEEN THE BOLT AND ISOLATION MOUNT, LOSS OF TORQUE DURING CYCLIC LOADING OF THE MOUNTING BOLT, AND SUBSEQUENT FATIGUE FAILURE OF THE BOLT.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=CHI89MA046) · AI Analytics · CC0 1.0*