Columbia, South Carolina
September 19, 2008
NTSB Number AAR-10/02
NTIS Number PB2010-910402
Adopted April 6, 2010
On September 19, 2008, about 2353 eastern daylight time, a Bombardier Learjet Model 60, N999LJ, owned by Inter Travel and Services, Inc., and operated by Global Exec Aviation, overran runway 11 during a rejected takeoff at Columbia Metropolitan Airport, Columbia, South Carolina. The captain, the first officer, and two passengers were killed; two other passengers were seriously injured. The nonscheduled domestic passenger flight to Van Nuys, California, was operated under 14 Code of Federal Regulations Part 135. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed.
The National Transportation Safety Board determines that the probable cause of this accident was the operator's inadequate maintenance of the airplane's tires, which resulted in multiple tire failures during takeoff roll due to severe underinflation, and the captain's execution of a rejected takeoff (RTO) after V1, which was inconsistent with her training and standard operating procedures.
Contributing to the accident were (1) deficiencies in Learjet's design of and the Federal Aviation Administration's (FAA) certification of the Learjet Model 60's thrust reverser system, which permitted the failure of critical systems in the wheel well area to result in uncommanded forward thrust that increased the severity of the accident; (2) the inadequacy of Learjet's safety analysis and the FAA's review of it, which failed to detect and correct the thrust reverser and wheel well design deficiencies after a 2001 uncommanded forward thrust accident; (3) inadequate industry training standards for flight crews in tire failure scenarios; and (4) the flight crew's poor crew resource management (CRM).
The safety issues discussed in this report focus on criticality of proper aircraft tire inflation; maintenance requirements and manual revisions for tire pressure check intervals; tire pressure monitoring systems; airplane thrust reverser system design deficiencies; inadequate system safety analyses by the FAA and Learjet; inadequate level of safety in the certification of changed aeronautical products; flight crew training for tire failure events; flight crew performance, including the captain's action to initiate an RTO after V1, the captain's experience, and CRM; and considerations for tire certification criteria. Safety recommendations concerning these issues are addressed to the FAA.
The National Transportation Safety Board makes the following recommendations to the Federal Aviation Administration:
Provide pilots and maintenance personnel with information that (1) transport-category aircraft tires can lose up to 5-percent pressure per day, (2) it may take only a few days for such tires to reach an underinflation level below what the aircraft maintenance manual specifies for tire replacement, and (3) the underinflation level that would require tire replacement is not visually detectable. (A-10-46)
Require that all 14 Code of Federal Regulations Part 121, 135, and 91 subpart K operators perform tire pressure checks at a frequency that will ensure that the tires remain inflated to within aircraft maintenance manual-specified inflation pressures. (A-10-47)
Require that aircraft maintenance manuals specify, in a readily identifiable and standardized location, required maintenance intervals for tire pressure checks (as applicable to each aircraft). (A-10-48)
Allow pilots to perform tire pressure checks on aircraft, regardless of whether the aircraft is operating under 14 Code of Federal Regulations Part 91, Part 91 subpart K, or Part 135. (A-10-49)
Require tire pressure monitoring systems for all transport-category airplanes. (A-10-50)
Identify the deficiencies in Learjet's system safety analyses, both for the original Learjet 60 design and for the modifications after the 2001 accident, that failed to properly address the thrust reverser system design flaws related to this accident, and require Learjet to perform a system safety assessment in accordance with 14 Code of Federal Regulations 25.1309 for all other systems that also rely on air-ground signal integrity and ensure that hazards resulting from a loss of signal integrity are appropriately mitigated to fully comply with this regulation. (A-10-51)
Revise available safety assessment guidance (such as Advisory Circular 25.1309-1A) for manufacturers to adequately address the deficiencies identified in Safety Recommendation A-10-51, require that designated engineering representatives and their Federal Aviation Administration (FAA) mentors are trained on this methodology, and modify FAA design oversight procedures to ensure that manufacturers are performing system safety analyses for all new or modified designs that effectively identify and properly mitigate hazards for all phases of flight, including foreseeable events during those phases (such as a rejected takeoff). (A-10-52)
Revise Federal Aviation Administration Order 8110.48 to require that the most current airworthiness regulations related to equipment, systems, and installations (14 Code of Federal Regulations 25.1309) are applied to all derivative design aircraft certificated as changed aeronautical products. (A-10-53)
Review the designs of existing derivative design aircraft that were certificated as changed aeronautical products against the requirements of the current revision of 14 Code of Federal Regulations 25.1309 and require modification of the equipment, systems, and installations to fully comply with this regulation. (A-10-54)
Define and codify minimum simulator model fidelity requirements for tire failure scenarios. These requirements should include tire failure scenarios during takeoff that present the need for rapid evaluation and execution of procedures and provide realistic sound and motion cueing. (A-10-55)
Once the simulator model fidelity requirements requested in Safety Recommendation A-10-55 are implemented, require that simulator training for pilots who conduct turbojet operations include opportunities to practice responding to events other than engine failures occurring both near V1 and after V1, including, but not limited to, tire failures. (A-10-56)
Require that pilots who fly in 14 Code of Federal Regulations (CFR) Part 135 operations in aircraft that require a type rating gain a minimum level of initial operating experience, similar to that specified in 14 CFR 121.434, taking into consideration the unique characteristics of Part 135 operations. (A-10-57)
Require that pilots who fly in 14 Code of Federal Regulations (CFR) Part 135 operations in an aircraft that requires a type rating gain a minimum level of flight time in that aircraft type, similar to that described in 14 CFR 121.434, taking into consideration the unique characteristics of Part 135 operations, to obtain consolidation of knowledge and skills. (A-10-58)
Require that tire testing criteria reflect the actual static and dynamic loads that may be imposed on tires both during normal operating conditions and after the loss of one tire and consider less-than-optimal allowable tire conditions, including, but not limited to, the full range of allowable operating pressures and acceptable tread wear. (A-10-59)
As a result of this investigation, the NTSB issued the following safety recommendations to the Federal Aviation Administration on July 17, 2009:
Require Learjet to change the design of the Learjet 60 thrust reverser 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)
Safety Recommendations A-09-55 through -58 and -60 (previously classified "Open-Response Received") are classified "Open-Acceptable Response" in this report. Safety Recommendation A-09-59 (previously classified "Open-Response Received") is classified "Open-Acceptable Alternate Response" in this report. These classifications are discussed in section 2.3.2 of this report.