McDonnell Douglas DC-10-10 N1820U

Summary

On 28 October 1991 at about 15:05 local time, a McDonnell Douglas DC-10-10 registered N1820U, operated by United Airlines, was involved in an incident near Las Vegas, Nevada, United States. 179 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

28 October 1991 at 15:05

Classification

Incident

Location

Las Vegas, Nevada, United States

Coordinates

Not recorded

Aircraft

McDonnell Douglas DC-10-10

Registration

N1820U

Category

Airplane

Engines

3

Operator

United Airlines

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Los Angeles → Denver

Aircraft damage

Minor

Weather

VMC

Light

Day

NTSB number

LAX92IA027

Nobody was injured.

RUPTURE OF A FORWARD PRESSURE BULKHEAD BECAUSE OF CYCLICALLY INDUCED METAL FATIGUE. FACTORS WHICH CONTRIBUTED TO THE INCIDENT WERE: THE OPERATOR'S DECISION NOT TO STRUCTURALLY MODIFY ITS AIRPLANE IN ACCORDANCE WITH THE MANUFACTURER'S BUT RATHER TO RELY ON THE MANUFACTURER'S ALTERNATIVE RECOMMENDATION OF PERFORMING REPETITIVE VISUAL INSPECTION IN THE SUSPECT AREA: AND THE OPERATOR'S FAILURE TO UTILIZE AN INSPECTION PROGRAM ADEQUATE TO VISUALLY DETECT CRACK DEVELOPMENT IN A PREVIOUSLY IDENTIFIED SUSPECT AREA.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

WHILE CLIMBING THRU 35,000 FT FOR A CRUISE ALTITUDE OF 37,000 FT, THE CREW HEARD A LOUD 'THUMP' & THE ACFT DEPRESSURIZED. AS THE CREW DESCENDED TO 11,000 FT, THE CABIN ALTITUDE CLIMBED TO 30,000 FT. THE FLT DIVERTED TO A NEARBY ARPT & SAFELY LANDED. EXAM OF THE ACFT DISCLOSED THAT REPETITIVE PRESSURIZATION CYCLES CAUSED THE INITIATION OF A FATIGUE CRACK & THE RESULTANT RUPTURE OF A FORWARD PRESSURE BULKHEAD. OVER 14 YRS EARLIER, DOUGLAS ISSUED SERVICE BULLETINS ADVISING OPERATORS THAT LEAKS COULD OCCUR IN THE FWD PRESSURE BULKHEAD AREA BECAUSE OF METAL FATIGUE. DOUGLAS RECOMMENDED THAT SPECIFIC CORRECTIVE ACTION BE TAKEN WHICH INVOLVED INSPECTING THE AREA AT 1,500 HOUR INTERVALS OR MAKING PERMANENT STRUCTURAL AIRFRAME MODIFICATIONS. CONTRARY TO THE MAJORITY OF ACFT OPERATORS, UNITED CHOSE NOT TO STRUCTURALLY MODIFY THIS ACFT. RATHER, IT CHOSE TO PERFORM RECURRING VISUAL INSPECTIONS FOR LEAKS IN THE SUSPECT AREA. THE ACFT'S PRESSURE BULKHEAD RUPTURED 1,367 HRS AFTER IT LAST INSPECTION.

Quoted verbatim from the NTSB record.