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NTSB attributes towing vessel engine fire to loose bolts on rod cap

Mar 23, 2016 04:45 PM

Loose bolts were likely to blame for an engine room explosion and fire that caused $3.8 million in damage on a Mississippi River towing vessel in 2014, investigators have determined. 

Dennis Hendrix’s engines were running at a high load level as it tried to overtake another boat just north of Baton Rouge, La., on Oct. 31, 2014. The engine room burst into flames. 

“The probable cause of the engine room fire on board the Dennis Hendrix was a catastrophic failure of the starboard main engine, resulting from loose bolts on the No. 5 cylinder rod cap, while the engine was operating at a high load condition,” the National Transportation Safety Board (NTSB) said in its report. 

At 0742, the 180-foot Hendrix was upbound and pushing 24 loaded barges when the fire started. Crewmembers fought the conflagration and other vessels assisted, but it burned until midafternoon. None of the 10 crewmembers were injured, and no environmental damage was reported. The NTSB said Hendrix sustained $3.8 million in losses. American Commercial Lines (ACL) in Indiana owns and operates Hendrix.

About 45 minutes before the incident, one of Hendrix’s two chief engineers was on duty in the engine room. The boat’s three engines — medium-speed, 16-cylinder turbocharged diesels, each driving a propeller via a set of reduction/reversing gears — were operating at about 840 rpm. Exhaust gas temperature, oil pressure and fuel pressure were normal.

At 0730, Hendrix approached the towing vessel Ron Hunter, which was transiting in the same direction. Concerned about a possible conflict, the Hendrix captain increased speed to a maximum 900 rpm on all three engines so that he could overtake Hunter, owned by Hunter Marine in Tennessee. 

In the lower engine room, Hendrix’s on-duty chief engineer was checking fuel-rack readings. He saw that the rack on the starboard engine was full, indicating that the fuel-rack positions controlled by the engine’s governor were at maximum. He heard a “laboring” sound from the starboard engine and went to the upper engine room to check the fuel control, NTSB investigators wrote. 

“As he reached for the door, the starboard engine exploded and blew out the windows on the starboard side of the engine room,” the report said. The starboard engine emitted flames.

The Hendrix captain heard the explosion and saw a reflection of flames and black smoke in a window on the starboard side of the wheelhouse. He took all three engines out of gear and sounded a general alarm. Hendrix lost speed at 0742. The crew gathered on the main deck to combat the engine room fire. Their firefighting efforts began on the starboard side, where the windows had blown out. 

Hendrix was equipped with a carbon-dioxide fixed fire suppression system in the engine room and, once all 10 crew were accounted for, the captain ordered the chief engineer to activate the system. At 0750, the Coast Guard and ACL were notified about the fire. The Coast Guard broadcast a request for nearby vessels to assist.

Hendrix’s chief engineer went to the emergency fuel shut-off station on the outer deck by the starboard door to the engine room to close fuel-supply valves to the engines. Closing the valves required additional help from the crew. After they were shut, Hendrix lost electrical power, and its emergency battery power was activated to run communications equipment and lighting. The crew used a portable, engine-driven fire pump to draw water from the river in order to combat the fire.

Because Hendrix was no longer moving under its own power, Ron Hunter took the boat and barges under tow to the right ascending riverbank and away from traffic.

That morning, eight boats helped with towing and firefighting. In the afternoon, two Exxon Mobil boats from Baton Rouge arrived, and their crews extinguished the fire with foam. The Hendrix crew gathered their personal items and were transferred ashore in a small skiff. A physician checked them for injuries, and they were tested for alcohol and drugs. All results were negative.

The Hendrix engine room was heavily damaged, and the rest of the vessel’s spaces were damaged by heat, smoke and water. “Post-accident surveys conducted by the Coast Guard and ACL described distorted decks and bulkheads, burned and charred wooden structural members, and soot and smoke damage throughout the main accommodation deck,” the NTSB wrote.

The greatest damage was in the vicinity of the starboard engine. One of the crankcase doors was blown out on its starboard side. Inside the crankcase door opening, parts of the bottom basket for the connecting rod of piston No. 5 were found. The bottom basket had separated from the rod. The piston and piston skirt were fragmented and deformed. On top of the engine, rocker-gear covers had melted. The crankcase door that blew out was found in the bilge between the engine and the starboard lube-oil tank.

The crankcase door had struck a nearby bank of valves for the lube oil tanks. Some of the valves had missing handles that had sheared off. The damaged No. 5 piston and the connecting rod assembly were removed from the starboard engine and sent to consultants Busch and Associates Inc. in Slidell, La.  

A report by Busch to ACL said that the No. 5 piston and connecting rod assembly failed because of loose bolts on the lower basket, causing fatigue failure of the blade and rod and upper connecting rod bearing. The report and its findings were shared with the engine’s manufacturer and service provider. 

ACL gave the investigators documents from its last overhaul of the starboard engine in late 2011. At that time, the engine was rebuilt with new parts from its manufacturer. New crankshafts were installed and the blocks were line-bored. 

The last maintenance jobs on the starboard engine were a clutch replacement in June 2014 and a fuel-injector replacement in July 2014, both of which were done ahead of required schedules. And in June 2014, the crew conducted a biannual maintenance inspection, which required a general tune-up, torque checks and inspection of piston rings, liners, cam lobes and rollers, air filtration and other engine components. The inspection form, completed on June 4, 2014, called for testing the torque between the basket and the connecting rod. To comply with the engine maintenance manual, the required torque for basket to rod was 190 foot-pounds and for rod to basket was 75 foot-pounds. The torque test was satisfactory. Everything tested during the inspection was within limits specified on the form, and the crew had no findings or comments.

Any additional onboard records of engine readings and maintenance were destroyed in the fire, according to investigators.

ACL told the NTSB that the starboard propeller on Hendrix sustained minor damage before Oct. 21, 2014, from a “drift in the river.” The crew checked the firing pressure of the starboard engine cylinders that Oct. 21 and 24. The pressure was within 10 percent of the mean, and the cylinders performed normally. But the damaged propeller needed replacement — which, as it turns out, was scheduled to be done after the voyage when the fire occurred.

ACL provided investigators with vessel performance data from before and after the starboard propeller was damaged. On Oct. 22, or after the propeller damage, the starboard engine operated at 901 rpm while pushing a load of barges, and the engine “dead racked”— meaning it needed full fuel delivery. Two days earlier and before the propeller was damaged, the engine did not dead rack, even though it operated at 905 rpm while pushing that same load.

On Oct. 31, because of the damaged propeller and the additional rpm that was required to overtake Ron Hunter, the starboard engine was under a greater load and required a heavier rack when the fire occurred, the report said. 

ACL didn’t respond to requests for comment. 

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