NTSB Factual Report

HISTORY OF FLIGHT

On February 4, 2007, about 2255 eastern standard time, a Boeing/McDonnell-Douglas DC-8-71F, Colombian registration HK-4277, operated by Tampa Airlines as flight 724, an unscheduled international cargo flight, from Medellin, Colombia, to Miami, Florida, had the right main landing gear collapse, during landing rollout on runway 09R, at Miami International Airport. Instrument meteorological conditions prevailed at the time, and an instrument flight rules flight plan was filed. The aircraft received minor damage, and the captain, first officer, and flight engineer were not injured. The flight originated at Rio Negro Airport (SKRG), Medellin, Colombia, the same day, about 1955.

According to the captain, after making a normal approach and landing on runway 9, during the landing rollout, while the airplane was at a speed of about 100-120 knots, and while the thrust reversers were deployed, the airplane began to lean and veer to the right. He said that he initially thought it may have been due to the crosswind, but he soon realized that the landing gear had collapsed. The captain estimated that when the airplane began to lean and veer it was positioned in the vicinity of taxiway T-2, and the airplane stopped in the vicinity of taxiway U. The flight crew then evacuated the airplane onto the taxiway via the L1 door slide.

The Director of Operations for Tampa Cargo stated that the DC8's landing weight at Miami, was 241,000 pounds, and it was loaded with cut flowers for Valentines Day. The airplanes maximum landing weight is 258,000 pounds, and it had 19,000 pounds of fuel on board when it landed.

DAMAGE TO AIRPLANE

Examination of the airplane by the NTSB, prior to recovery from the runway showed that the airplane sustained minor damage. There was visible damage to the right main landing gear, and some associated parts in its wheel well. Specifically, the right main landing gear down lock link and the trapezoidal fitting had fractured, with the right main landing gear having collapsed in the normal plane of retraction. In addition, the landing gear's actuator arm had about a 90-degree bend at its mid span. The airplane had come to rest on the engine nacelles for the numbers 3 and 4 engines, however the right wing did not contact the runway.

PERSONNEL INFORMATION

The captain, age 46, held a Colombian airline transport pilot certificate, with ratings for both single and multiengine land airplanes. He also possessed type ratings for the DHC-6, B-707, and the DC-8. He also held a Colombian first class medical certificate, dated January 5, 2007, with no stated limitations. His last recurrent training had been completed on October 12, 2006. The captain had accumulated 18,000 hours of flight experience, and 12,000 as pilot-in-command, of which 3,500 was in the some make and model as the incident airplane. He had flown 130 hours in the last 90 days, and 8 hours within the last 30 days.

The first officer, age 28, held a Colombian commercial pilot certificate, with ratings for both single and multiengine land and instrument airplanes. He also held a rating as copilot on the DC-8. In addition, he held a Colombian first class medical certificate, dated October 13, 2006, with no stated limitations, and his last recurrent training had been performed on October 12, 2006. The first officer had accumulated 3,050 hours of flight experience, of which 2,000 was in the some make and model as the incident airplane. He had flown 135 hours in the last 90 days, and 12 hours within the last 30 days.

The flight engineer, age 63, held a Colombian flight engineer certificate. In addition he held a Colombian first class medical certificate, dated December 15, 2006. His last recurrent training had been performed in September 2006.

AIRPLANE INFORMATION

According to information obtained from the FAA, the incident DC-8-61 was manufactured by McDonnell Douglas on June 21, 1968, as serial number 45976, fuselage number 372, and it began operation for United Airlines. The aircraft operated with Pratt and Whitney JT3D-3B engines as passenger carrying airplane. The aircraft was re-engined to CFM International CFM56-2C1 engines on September 17, 1982 and continued to be operated by United as DC-8-71, in passenger service.

The airplane was converted to a cargo carrying DC-8-71F in August of 1991, and began operation for TAMPA Cargo in February 2003, as registration HK-4277 (Colombian). The airplane had 95347 hours and 33849 cycles in service as of October 31, 2006.

FLIGHT RECORDERS

Both the cockpit voice recorder (CVR) and digital flight data recorder (DFDR) were secured immediately after the incident in accordance with Tampa Cargo's procedures, and promptly sent to the NTSB's Recorder Laboratory, Washington DC, for readout.

The DFDR was examined in the recorder laboratory and all pertinent parameters were noted to be consistent with those of a normal landing having been performed. The data showed that the airplane touched down on a heading of about 087 degrees, at about 144 knots, and registered a peak vertical acceleration at touchdown of 1.837g. At the point where the landing gear collapsed, the event was indicated by a roll angle that progressed to about 5 degrees right wing down, shortly after touchdown.

The CVR was auditioned at the NTSB's Audio Laboratory. All conversations were in Spanish, and after translation, the conversations proved to be unremarkable and were consistent with a normal landing having occurred.

WRECKAGE AND IMPACT INFORMATION

After initial examination by the NTSB the airplane was removed from runway 09R to a maintenance facility for further examination.

Disassembly of components of the right main landing gear torque tube showed that the outboard torque tube attach bolt had backed out from the piston prior to the incident. The torque tube is attached to the piston by an attach bolt, which is threaded and has a hole drilled in the end. The attach bolt is threaded into the piston and then is then torqued to 475 ft-lbs. The next step is to install the lockbolt, which retains the attach bolt in place. According to the Manager of Quality Assurance (QA) at Tampa Cargo, the attach bolt was not properly torqued and the lockbolt was installed, but not through hole in the end of the attach bolt. As a result, after 11cycles, the attach bolt backed out of the threaded area of the piston and the right main landing gear collapsed.

In addition, the QA Manager at Tampa Cargo told the FAA that during installation of the right main landing gear a maintenance personnel shift change had occurred, and the new shift was not informed by the outgoing shift what work still needed to be accomplished, which resulted in the right main landing gear being reassembled incorrectly.

Damaged landing gear parts were collected and sent to the NTSB's Metallurgical Laboratory, Washington DC, where they were examined optically. The examination revealed that the damage parts exhibited signatures consistent with that of overstress separations. No preexisting cracking or corrosion was noted during the optics examination.

NTSB Probable Cause

Improper torque of a landing gear lockbolt by company maintenance personnel during landing gear installation.