Kegworth air disaster
From Freepedia
| Kegworth Air Disaster | |||
|---|---|---|---|
| Summary | |||
| Date | January 8 1989 | ||
| Type | Mechanical failure | ||
| Accident site | Kegworth, Leicestershire | ||
| Fatalities | 47 | ||
| Injuries | 79 | ||
| Aircraft | |||
| Aircraft type | Boeing 737-400 | ||
| Operator | British Midland | ||
| Tail number | G-OBME | ||
| Passengers | 118 | ||
| Crew | 8 | ||
| Survivors | 79 | ||
The Kegworth air disaster occurred on January 8, 1989, when British Midland Flight 92, a Boeing 737-400, G-OBME owned by British Midland crashed onto the embankment of the M1 motorway, short of the runway of East Midlands Airport, Leicestershire, close to the village of Kegworth.
Forty-seven of the 118 passengers lost their lives (39 at the scene, 8 later). All eight of the flight crew survived the accident. Of the 79 survivors, 5 had minor injuries and 74 were seriously injured. Surprisingly, no one on the motorway was hurt (and no vehicles damaged).
The aircraft was on a scheduled flight from Heathrow to Belfast in Northern Ireland. After take-off from Heathrow, the twin-engined plane was climbing through 28,000 feet when the no.1 engine suffered a turbine blade detachment. The flight was diverted to East Midlands, which it should have been able to reach flying on one engine. However, the crew misidentified the failed engine and shut down the correctly functioning no. 2 engine. With the damaged engine providing only limited power, the aircraft was unable to reach the emergency destination airport, and hit the ground short of the runway while attempting to land.
After the initial blade deatchment, the crew were aware of the situation by a smoke smell and abnormal vibration, as well as numerous cockpit warnings. They had no way to visually check the engines from the cockpit but numerous instruments indicated which engine was malfunctioning, however, the pilots' limited experience and lack of training on the 2 month old aircraft contributed to them shutting down the wrong engine.
The Captain of the flight believed the no.2 engine was malfunctioning due to the smell of smoke, because in previous Boeing 737 variants, bleed air from the engines for the air conditioning system was taken from engine no.2. However, starting with the Boeing 737-400 variant, Boeing redesigned the system so both engines fed it. Several cabin staff and passengers also noticed that the no. 1 engine had a stream of unburnt fuel igniting in the jet exhaust, but this information was not passed to the flight crew. When the pilots shut down the no. 2 engine, the vibration and smoke smell ceased immediately, which confirmed in their minds that they had dealt with the problem.
As it turned out, this was simply a fateful coincidence, as when the auto-throttle was disengaged to shut down engine no.2, the fuel flow to no.1 engine was reduced and the excess fuel which was igniting in the jet exhaust previously no longer existed, therefore the ongoing damage was reduced and the smoke and vibration seized.
However during the final approach to East Midlands Airport, more fuel was pumped into the damaged engine to maintain speed, which caused it to cease operating entirely and burst into flame. The captain ordered the no.2 engine to be started at this point via windmilling, using the air flowing through the engine to rotate the turbine blades and start the engine, however the crew never managed to achieve this. The captain managed to keep the aircraft airborne long enough to avoid crashing landing in the village of Kegworth, however just before it reached the motorway, the tail hit the ground and the aircraft bounced back into the air and over the M1 motorway, crashing on the embankment and breaking up into three pieces. Amazingly no one on the ground was invovled.
It was later discovered after analysis of the engine from the crash that the turbine blades of the updated CFM56 engine used on the 737-400 were subject to abnormal amounts of vibration when operating at high power settings above 25,000 ft. As they were only an upgrade to exisiting engine in-flight testing was not mandatory and as such, the engines were only ever tested in the laboratory. Upon this discovery all 737-400 (around 100 at that time) were grounded and the engines modified. Since the accident it has also become mandatory to in-flight test all turbofan engines, wherever they are a brand new design or a modification.
This unnoticed vibration created excessive metal fatigue in the turbine blades and on G-OBME this caused one of the turbine blades to fail structually and go tearing through the engine. This damaged the engine terminally and also upset its delicate balance, causing a reduction in power. The autothrottle attempted to compensate for this by increasing the fuel flow to the engine, however the damaged engine was unable to burn all the additional fuel, with much of it igniting in the exhaust flow, thus creating a large trail of flame behind the engine. The increase in engine RPM this gave also increased vibration from the now unbalanced engine.
Evaluation of the injuries sustained led to considerable improvements in aircraft safety and emergency instructions for passengers. The official report into the disaster made 31 safety recommendations.
There is a memorial to "those who died, those who were injured and those who took part in the rescue operation", in the village cemetery in nearby Kegworth, together with a garden made using soil from the crash site.
See also
External links
Categories: History of Leicestershire | Airliner crashes caused by mechanical failure | 1989 | Disasters in the United Kingdom
