System Cited In 2008 Accident In South Carolina

In a letter to FAA Administrator Randy Babbitt, acting NTSB chair Mark Rosenker is recommending that the FAA require a re-design of the thrust reverser system on Learjet 60 models.

The recommendation stems from a 2008 accident in South Carolina, in which a Bombardier Learjet 60 operated by Global Exec Aviation overran runway 11 while departing Columbia Metropolitan Airport in Columbia, South Carolina. The pilot, copilot, and two of the four passengers were killed. The two other passengers were seriously injured, and the aircraft was destroyed by postcrash fire.

The letter states, in part:
"Postaccident examination of markings and tire debris indicated that the right outboard tire failed first because of underinflation, followed by failures of the other tires.2 Examination of the engines revealed evidence consistent with high thrust in both engines and indicated that the thrust reversers were stowed when the airplane hit the embankment.

In March 2009, Learjet published an FAA-approved temporary flight manual (TFM) change in procedures, which described improved methods for quickly recognizing and handling situations when inadvertent stowage occurs. However, the NTSB is concerned that Learjet 60 pilots are not sufficiently trained to recognize that a failure could occur during takeoff as well as landing phases of flight and could subsequently result in the loss of system logic control requirements for maintaining deployed thrust reversers during a rejected takeoff. The design of the Learjet 60 thrust reverser system (and potentially similarly designed systems for Raytheon Hawker 1000 business jets) is also of concern to the NTSB."

Lear 60 File Photo

The NTSB has made the following recommendations in conjunction with this incident:

• Require Learjet to change the design of the Learjet 60 thrust lever system in future-manufactured airplanes so that the reverse lever positions in the cockpit match the positions of the thrust reverser mechanisms at the engines when the thrust reversers stow. (A-09-55)
• Once design changes are developed per Safety Recommendation A-09-55, require Learjet 60 operators to retrofit existing airplanes so that the reverse lever positions in the cockpit match the positions of the thrust reverser mechanisms at the engines when the thrust reversers stow. (A-09-56)
• Require Learjet to develop and install improved aural or visual cues on future-manufactured Learjet 60 airplanes that would allow pilots to recognize an inadvertent thrust reverser stowage in a timely manner. (A-09-57)
• Once improved aural or visual cues are developed per Safety Recommendation A-09-57, require Learjet 60 operators to install those cues on existing Learjet 60 airplanes. (A-09-58)
• Require that all Learjet 60 pilots receive training, for takeoff as well as landing phases of flight, on recognizing an inadvertent thrust reverser stowage, including the possibility that the stowage can occur when the requirements for deploying thrust reversers are not fully met, such as when the air/ground sensor squat switch circuits are damaged. (A-09-59)
• Evaluate the design of the thrust reverser controls and indications in Raytheon Hawker 1000 business jets for potential thrust reverser failure modes that are similar to those identified in Learjet 60 airplanes and implement necessary changes. (A-09-60)

FMI: www.ntsb.gov