Story ID: 111ChallengerTiresSept15
Bombardier Challenger Tire Failures Spur Safety Questions
By: Kerry Lynch
Caption: Sage-Popovich chief questions whether a series of tire failures are related to possible manufacturing issue.
Word Count: 976
Reports of more than a couple of dozen failures of a certain Goodyear tire used on older Bombardier Challengers are spurring operators to question a potential safety issue with it. Leading the charge is Nick Popovich, president of aircraft repossession specialist Sage-Popovich. 

The issue surfaced when a tire failed on Popovich’s own 1983 Bombardier Challenger 601, N600NP, on March 1 this year at Marco Island, Fla. The aircraft was damaged when it ran off the runway into sand and the nose landing gear collapsed.

Popovich said video footage of the accident depicts the number-one tire failing on touchdown. After the accident, Popovich’s flight department investigated its training, crews, continuing education program, aircraft and maintenance history and standards.  “Nothing suggested a failure on our end,” he told the FAA.

When he later received a replacement aircraft, Popovich noticed a log entry related to a failure of the same tire part number. He also heard anecdotes of other failures and started to wonder if this was a common occurrence. He began surveying other operators about their experiences. Reports of 27 similar incidents flowed in from operators involving Goodyear tire Part Number 256K43-3 on the Challenger 600/601 series, he said. Popovich asked the FAA to look into the matter.

The FAA has been telling Popovich that the in-service tire events are being investigated by FAA Aircraft Certification Offices, the Small Airplane Director and Transport Airplane Directorate Safety Management Branch. The agency cautioned, however, that “tire failures on turbine-powered aircraft are quite common” and that it needs more data to determine whether there is a safety problem. The agency told Popovich that the information it has to date is “insufficient to determine root cause, or the actual consequences of the failures.”

When asked about the issue, Bombardier told AIN it is aware of Popovich’s concerns, but noted that the FAA has not found a safety issue. The company also noted that blown tires are often discarded, making it difficult to track a trend. But it pointed out, too, that the Challenger meets airworthiness requirements.

Goodyear told AIN it analyzed the tire on Popovich’s airplane at the time of the incident “and determined that its disablement occurred as a result of a common brake-related skid through, and was not due to any tread separation or manufacturing issue.” As for other reports, the company added it “responds to customer claims or complaints as we are notified.” In correspondence with operators, a Goodyear representative mentioned possible reasons for issues, including tire pressurization and foreign object damage. One of the letters suggested that if the problem were systemic, the company likely would have received an inquiry from Bombardier. The Goodyear representative, however, did mention the potential for a manufacturing issue if all the incidents involve the same tire size/part number. In that case, he said, “we might consider this a possibility.” 

While Popovich agrees that it is not unusual for tires to blow, the nature of the failure concerns him. In the incidents the tires failed in a similar manner, he asserts, with the tread separating from the core, which Popovich said might raise questions of bonding issues.

The National Transportation Safety Board is still investigating the accident involving Popovich’s aircraft, but the preliminary report notes that after touchdown, the pilot was unable to extend the ground spoilers and felt no deceleration when he applied moderate brakes and held the control yoke forward. He was also unable to deploy the thrust reversers. “The PIC informed the copilot there was no braking energy.” 

The FAA had cautioned that there is still no final determination in that accident. But Popovich has his own theory: “Thinking through the logic of aircraft systems leads one to wow [weight on wheels] system failure, i.e., the aircraft clearly thought it was in the air and therefore overrode the manual inputs of the crew for brakes, ground spoilers and reversers,” he told the FAA.

Such a theory is not without precedent. The NTSB described a wow failure in its report of the 2008 crash of a Learjet 60 that killed a well known Los Angeles DJ. The tires in that case were underinflated and failed.
Blown Tires Relatively Common
One operator in correspondence with Popovich reported having “a tire throw a big piece of tread. Can’t see where it was cut.” Others reported not only having a tread separation but also experiencing a wow fault. Another stated his aircraft had just incurred its third Goodyear tread separation and said he had met with another operator that had had either four or five similar incidents. Charter and management firm Solairus confirmed to AIN that it experienced two incidents this summer.

These issues involved tires that had logged between 29 and 141 landings. According to Popovich, the tires appeared to have had significant tread life remaining and no signs of misuse. Popovich theorizes that the failures stem from a lack of adhesion between tread rubber and nylon breaker ply and/or cords. This causes the outer ribs to separate from the tire and led to damaged airframes, he asserts.

According to Popovich, it appears that the tires involved were manufactured in Brazil between 2004 and last year.

Popovich worries that more incidents are occurring, but that because tire failures are not especially uncommon the incidents are not getting reported. He is convinced something must be done before someone gets hurt in an accident. Popovich was injured in his own accident and the aircraft was substantially damaged. “The situation is a danger, and this is the only tire approved for the aircraft,” he told the FAA in an email. In the meantime, he says he’s working to obtain approval to use different tires.