January 25, 2010
On September 19, 2008, a Learjet 60 aircraft operating under Part 135 crashed during a rejected takeoff at the Columbia, South Carolina airport. The accident resulted in four fatalities including two passengers and both crew members. Two additional passengers received serious injuries.
The National Transportation Safety Board (NTSB) investigation revealed that the accident aircraft’s tire pressure had not been checked in approximately three weeks. The tires on this aircraft experienced approximately 2% per day loss of pressure. The Board determined that the tire pressure at the time of the accident was approximately 140 psi. Recommended tire pressure for the tires is 219 psi.
The under-inflation of the four main landing gear tires resulted in the failure of all four main landing gear tires. The Board found fragments of the failed tires that revealed folded rubber and melted nylon used to produce the tires. In addition, hydraulic fluid was found on some tire fragments, confirming that the tire failure also compromised some elements of the aircraft hydraulic system.
Finally, the Board’s investigation identified that there is significant inconsistency in the operating community about the pilot’s role in ensuring correct tire pressure prior to take off. Visual inspection of high-pressure tires, such as those on the accident aircraft, will not reveal an improperly inflated tire. By the time a tire shows visual signs of poor inflation, the tire manufacturer will require that the under-inflated tire and the axle-mate (the other tire on the same landing gear) be replaced.
FAA Safety Alert
On January 6, 2011, the Federal Aviation Administration (FAA) recently issued a safety alert for operators (SAFO) stressing the importance of ensuring that aircraft tires are properly inflated and detailing the potential consequences that improper tire pressure can have on aircraft performance during taxi, takeoff and landing.
Pilots perform a preflight inspection of the aircraft to determine its airworthiness. Assuring the aircraft departs with the correct tire pressure is an important part of this airworthiness check. Pilots should consider the following:
- Know the nominal tire pressure for your tires.
- The proper pressure is between 95% and 105% of nominal tire pressure, depending upon conditions. Anything less than 90% of nominal tire pressure is considered a flat tire.
- A visual inspection of each tire is required to check for wear and foreign object damage but it will not adequately determine tire pressure.
- Check the tire pressure of each tire. Best practice is to carry a good, calibrated tire pressure gauge and be trained in its proper use. If company policy or regulations for the flight will not allow the flight crew to check tire pressure, then make arrangements to have the pressure checked by a qualified maintenance technician, even when away from home base.
- Temperature affects tire pressure. Therefore, consider the temperature implications of your arrival airport and plan pressure adjustments accordingly.
- Arrange for proper pressure adjustments, as needed, prior to each takeoff.
- Keep a log of pressure adjustments for useful trend information and provide this to maintenance personnel so issues can be identified, addressed and resolved.
Aircraft tires play the most significant role in stopping the aircraft during the execution of a rejected take-off. Tires will only perform as expected when they are maintained as specified by the tire manufacturer, the aircraft manufacturer and regulatory and guidance material. Operators should ensure they have developed appropriate procedures that maintain tire pressures within allowable limits.
For further information, consult the following resources:
- Your aircraft maintenance manual.
- FAA Advisory Circular AC 20-97B “Aircraft Tire Maintenance & Operational Best Practices”
- Review SAFO 11001: The Importance of Properly Inflated Aircraft Tire
- FAA Safety Alert for Operators (SAFO) “Dangers of Improperly Inflated Tires”
- Recent NTSB recommendations
- NTSB Report and Accident Investigation