# NTSB Incident CHI03IA097
> **Boeing 747-422** · 2003-04-01 · Chicago, IL, USA · NONE
## Event
- **NTSB number:** CHI03IA097
- **Event ID:** 20030410X00480
- **Type:** Incident
- **Date:** 2003-04-01
- **Location:** Chicago, IL, USA
- **Coordinates:** 41.979721, -87.904441
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 319
- **Total aboard:** 319
## Aircraft
- **Make:** Boeing
- **Model:** 747-422
- **Registration:** N175UA
- **FAR Part:** 121
- **Engines:** 4
- **Damage:** —
## Conditions
- **Light:** DAYL
- **Weather:** VMC
## Probable cause

Failure of company maintenance personnel to fully comply with published maintenance/inspection procedures, as well as the resulting inoperative drain heaters and restricted movement of the aileron control cables.  Contributing factors were the impeded waste water drain system due to the inoperative heaters and the reduced aileron control due to restricted movement of the control cables.

---
*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=CHI03IA097) · AI Analytics · CC0 1.0*