March 1, 2011: Fontaine Fifth Wheel sends service bulletin to customers telling them that the Ultra LT hitch used on semis may not lock properly and trailers can detach from tractors on the road. The bulletin also is sent to the National Highway Traffic Safety Administration.
April 15, 2011: NHTSA opens investigation to find out which tractor manufacturers use the Ultra LT.
May 13, 2011: Daimler Trucks North America recalls 2,281 Freightliner cabs to replace the locking bar on the hitches.
June 27, 2011: NHTSA closes investigation, says it knows other truck manufacturers used the Ultra LT on tractors and will work with Fontaine "to ensure that the remaining vehicles are identified and remedied."
July-September 2011: Paccar recalls 10 Kenworth trucks to fix the problem. Mack Trucks and Volvo Trucks recall a total of 129 cabs for the same issue.
April 4, 2012: Fontaine issues a second service bulletin telling customers that the hitches can have a bent lever that also can allow trailers to come loose. Problem is caused by "improper coupling techniques." NHTSA says it reviewed bulletin but took no action because warnings about proper product use are common.
Jan. 24, 2014: Trailer comes loose from International ProStar tractor on U.S. 50 east of Cincinnati. Plows into oncoming traffic, killing two men, each driving a pickup truck. Two others hurt.
August, 2014: Fontaine and Navistar report the crash to NHTSA as required by law. No NHTSA action is noted in records, but agency says it asked for more information in September.
November, 2014: Fontaine responds with report blaming crash on truck driver error in coupling trailer.
May 13, 2015: The company meets with NHTSA safety investigators to discuss a third service campaign to replace 6,000 Ultra LT hitches for unspecified "non-safety" issue.
June 9, 2015: NHTSA opens investigation to test the Ultra LT and estimates that 6,000 tractors are on the road with the potentially defective hitches. Fontaine says it will cooperate with the probe.
Sources: NHTSA documents, agency and Fontaine statements.