# NTSB CHI93IA035: McDonnell Douglas DC-8-71, N870SJ, Chicago, IL, November 13, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: November 13, 1992, 06:50 local (12:50 UTC)
- Place: Chicago, IL
- Location: 41.8500° N, 87.6501° W: Placed by OpenAirDocs: center of Chicago, IL, within about 9 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.8500&lon=-87.6501&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report September 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 15590
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI93IA035
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/15590/pdf
- Page: https://openairdocs.org/ntsb/CHI93IA035

## Probable cause

AN IMPROPER REPAIR OF THE RETRACT PIN BOSS AREA BY THE OVERHAUL FACILITY.

## Sequence of events

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

- Gear not retracted, climb - to cruise
  - landing gear,main gear - movement restricted
- Airframe/component/system failure/malfunction, climb - to cruise
  - landing gear,normal retraction/extension assembly - failure,total (contributing factor)
  - maintenance,major repair - improper, other maintenance personnel (cause)
  - landing gear,normal retraction/extension assembly - fatigue (contributing factor)

## Analysis

THE CREW OF THE MCDONNELL-DOUGLAS DC-8 CARGO AIRPLANE RETRACTED THE LANDING GEAR DURING ITS CLIMB TO CRUISE ALTITUDE. THE CREW ADVISED AIR TRAFFIC CONTROL THAT THE LANDING GEAR HAD NOT RETRACTED PROPERLY.  DURING AN ATTEMPT TO ENSURE THE LANDING GEAR WAS IN THE DOWN AND LOCKED POSITION THE CREW HEARD A LOUD BANG.  COINCIDENTAL WITH THE AIRCREW'S ACTIONS, A PERSON RESIDING IN A SINGLE FAMILY HOME REPORTED THAT A METAL OBJECT HAD PENETRATED HER HOME'S ROOF AND IMBEDDED ITSELF IN THE FLOOR.  THE AIRPLANE RETURNED TO LAND WITHOUT FURTHER INCIDENT. AN ON-SCENE INVESTIGATION REVEALED THE RIGHT MAIN LANDING GEAR RETRACT PIN HAD SEPARATED FROM THE LANDING GEAR LEG.  PORTIONS OF THE GEAR LEG RETRACT PIN BOSS AREA HAD SEPARATED AND WERE FOUND WEDGED ALONG SIDE THE GEAR ASSEMBLY.  SUBSEQUENT METALLURGICAL INVESTIGATION REVEALED THE PIN BOSS AREA HAD METAL FRACTURE FEATURES CONSISTENT WITH OVERLOAD, ONE OF WHICH WAS CONSISTENT WITH A PREEXISTING FRACTURE AREA.  THE PIN BOSS AREA HAD PREVIOUSLY BEEN OVER-BORED AND CHROME PLATED PRIOR TO A RETURN TO SERVICE.  THE AIRPLANE MANUFACTURER STATED THE PIN BOSS BORE SHOULD NOT BE CHROME PLATED.

## Aircraft

- Registration: N870SJ (not matched to a registry record)
- Reported make and model: McDonnell Douglas DC-8-71
- Category: Airplane
- Serial number: 46039
- Airframe hours: 27
- Engines: GE CFM56-2C1 turbo fan
- Damage: Minor damage
- Flight: Part 121
- Operator: Southern Air Transport
- Registered owner: Aero USA
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, May 21, 1992, 1,554 hours before
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 7,850 total, 338 in this make and model

## Weather

- Conditions: Visual (VMC), Not reported
- Wind: 330° at 10 knots
- Visibility: 5 statute miles
- Lowest ceiling: 15,000 ft overcast
- Temperature: 36 °F
- Observed at: ORD, 10 nm away

## 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 19921113055949I](https://openairdocs.org/incident/19921113055949I), Nov 13, 1992: Doug DC871F, Chicago, IL, Minor damage. Landing gear malfunction after takeoff. Returned. Landed safely. Right gear retract cylinder attach boss had failed

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.

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