Incident Overview
On 4 February 1999, a McDonnell Douglas MD90 (registration SE-DMG) operated a public transport flight into London Heathrow Airport. The aircraft, manufactured in 1996 and powered by two IAE V2525-D5 turbofan engines, was on approach with 3 crew and 83 passengers aboard. No injuries were reported among occupants.
Landing Gear Indication Issue
During approach, the crew observed green indicator lights confirming the nose and right main landing gear were down and locked, but no green indication for the left main landing gear. The crew recycled the landing gear, but the left main gear still did not show a green indication. After executing a go-around, they assessed the situation and concluded the problem was most likely due to an indication fault.
Emergency Gear Extension
Following the Emergency Checklist, the crew deployed the landing gear using the emergency blow-down system. Unlike normal hydraulic extension, the emergency system leaves the main landing gear doors fully open because no hydraulic pressure is available to close them after the legs extend. These open doors have steel skid plates on their lower edges to prevent abrasion damage from runway contact.
Landing and Damage
The aircraft subsequently landed on Runway 27R. During the landing, the open landing gear doors contacted the runway, damaging two runway centerline lights and leaving a score mark in the tarmac.
Post-Flight Inspection
After passengers disembarked at the gate, engineering staff confirmed an indication system fault affecting both green indicator lights for the left main landing gear.