The problems with JetBlue Flight 292 marked at least the seventh time that the front landing gear of an Airbus jet has locked at a 90-degree angle, forcing pilots to land commercial airliners under emergency conditions, according to federal records.
No one has been injured in the incidents, which span about a decade. There are more than 2,500 planes from the Airbus 320 family, which includes the Airbus 318, 319 and 321 models, in operation worldwide. Aviation safety officials Thursday said the planes have a good safety record.
In the most recent case, JetBlue's flight from Burbank to New York's John F. Kennedy International Airport, carrying 140 passengers, was forced Wednesday to make an emergency landing at Los Angeles International Airport. The plight of the aircraft was televised nationwide, beginning with the plane circling over the California coast and ending at an LAX runway with a landing marked by fire streaming from the plane's front wheels.
Howard Plagens, a senior air safety investigator with the National Transportation Safety Board, which is investigating Wednesday's incident, called problems with landing gear "common."
At a news conference Thursday at the Proud Bird Restaurant outside LAX, he said he believed that passengers had no reason for concern about the safety of the Airbus fleet.
"How many Airbus A320s are out there?" he said, adding that the number of times the wheels have locked is small.
"Incidents happen every day" involving landing gear on all types of planes, he said.
The locking of the nose landing gear on Airbus jets is one of several recurring problems with the plane's nose landing gear.
A Canadian study issued last year documented 67 incidents of nose-landing-gear failures on Airbus 319, 320 and 321 aircraft worldwide since 1989.
Plagens said the A320 wasn't grounded after previous incidents involving the nose landing gear because "they did do fixes for those things."
After the initial investigation, the NTSB will look at maintenance records for other Airbus A320 aircraft, Plagens said. Investigators will review other instances involving the plane's nose wheel, as well as modifications recommended to fix the problem.
"If we find a pattern, we'll certainly do something," he said.
NTSB officials expect the investigation into Flight 292's emergency landing to take six to nine months. They have removed the cockpit voice recorder and the digital flight data recorder from the plane and sent them to Washington for evaluation.
In the next few days, safety officials will decide whether to send the entire nose-landing-gear assembly to New York, where mechanics will take it apart piece by piece and reassemble it to try to re-create the failure.
The landing gear on the nose of the A320, also known as the nose wheel, is a big, bulky system controlled by a computer. The computer gives commands to an electrical system, which in turn operates the hydraulics that move the gear up and down, moving the wheels into proper position for both landing and storage.
The problem that caused the wheel on Flight 292 to lock in the wrong position could have been caused by the electrical system, the hydraulics or some other part of the assembly, Plagens said.
The 3-year-old aircraft was towed to a Continental Airlines hangar at LAX for evaluation. It remained there Thursday. Airbus engineers were flying to Los Angeles on Thursday night to help NTSB investigators determine what caused the incident.
The circumstances of Wednesday's incident bear strong similarities to other documented incidents of Airbus 320 and 319 airplanes experiencing front wheels locking in the wrong position.
Two causes for the misaligned front wheels have been found.
A problem with misaligned wheels on a 1999 America West flight into Columbus, Ohio, was caused by a faulty seal on a valve. That design flaw had been known before the flight because of a previous incident and had been the subject of an advisory to airlines using the Airbus 320 planes. The fix had not yet been made on the aircraft involved in the emergency landing. After the flight, federal safety officials issued an order that required the repair.
In November 2002, another JetBlue flight to New York experienced a problem similar to the one Wednesday.
Three weeks later a United Airlines flight into Chicago had the same problem, landing with sparks spewing from the nose-gear wheels.
Investigators found that the force of the landing had ground one wheel all the way to the axle and the other nearly as far.
In those two cases, as well as two flights in other countries, the problems were traced to improper installation of a hydraulic shock absorber.
That problem also led to advisories to airlines, detailing mistakes that maintenance workers could make in installing the hydraulic shock absorber. The advisories warned that failure to comply with proper installation instructions "is dangerous for aircraft safety."