# NTSB DEN90IA016: Boeing 737-322, N344UA, Rapid City, SD, October 27, 1989

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: October 27, 1989, 12:45 local (18:45 UTC)
- Place: Rapid City, SD
- Coordinates: 44.049865, -103.420616 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.0499&lon=-103.4206&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 40 uninjured
- Status: Completed, report August 26, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17850
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90IA016
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17850/pdf
- Page: https://openairdocs.org/ntsb/DEN90IA016

## Probable cause

THE INFLIGHT FAILURE OF THE RECIRCULATING FAN UNIT AND SEVERAL AIR DUCT TEMPERATURE LIMITING SENSORS.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, climb - to cruise
  - air cond/heating/pressurization - failure,partial (cause)
  - air cond/heating/pressurization,cabin temp control - failure,total (cause)

## Analysis

WHILE CLIMBING THROUGH FLT LEVEL 280, THE FLT CREW DETECTED AN ODOR AND SOME SMOKE IN THE COCKPIT AND CABIN. THE CAPTAIN ELECTED TO RETURN TO THE DEPARTURE AIRPORT & HE LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE PERSONNEL INSPECTED THE ACFT AND REPLACED SEVERAL AIR CONDITIONING SYSTEM TEMPERATURE SENSORS AND THE RECIRCULATING FAN ASSEMBLY. THESE ACTIONS CORRECTED THE PROBLEM AND THE ACFT WAS RETURNED TO SERVICE.

## Aircraft

- Registration: N344UA (not matched to a registry record)
- Reported make and model: BOEING 737-322
- Category: Airplane
- Serial number: 24248
- Airframe hours: 324
- Engines: GE CFM56 20000 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: United Airlines
- Registered owner: Wilmington Trust Co Trustee
- Airworthiness certificate: Standard, Normal
- Destination: FSD, SIOUX FALLS, SD
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; flight engineer, airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 7 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 59 °F, dew point 28 °F
- Altimeter: 29.00 inHg
- Observed at: RAP

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19891027057769I](https://openairdocs.org/incident/19891027057769I), Oct 27, 1989: Boeing 737322, Rapid City, SD. Smoke in aircraft on departure. Returned. Smoke again while taxiing. Evacuated via slides.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.