A series of critical, but apparently preventable, shaft bearing failures are plaguing the Navy's latest LPD17 class amphibious transport ships, built by Northrop Grumman Shipbuilding. Five of the ships have been delivered and are in service; four remain to be built.

USS New York LPD21

The flagship of the series, USS New York, gained international fame with its construction incorporating with 7.5 tons of steel from the World Trade Center forged into her bow.


The ships are outfitted with four massive Fairbanks Morse (a division of EnPro Industries) Colt-Pielstick PC 2.5 STC diesel propulsion units. Each 16-cylinder engine weighs 84 metric tons, and is rated at just over 10,000 brake horsepower at 520 RPM. The cranks sit in nine main bearings, fed by high-volume externally pressurized oiling systems. In the LPD17 ships, two engines feed one reduction gearbox and prop. Engine rooms are entirely automated.

Colt-Pielstic PC 2.5 STC

Crankshaft bearing problems have been showing up for more than a year, inhibiting the ships' ability to perform or stay in service. Once crankshaft vibrations set up in the 84-metric-ton engine, the vibrations can become so powerful that the engine and gearbox can literally be destroyed, along with its entire mounting structure.

The attention-grabbing New York had a humiliating return to dock, under reduced power, during her very first weeklong shakedown after being put in the water. Worsening crankshaft vibrations were setting up in all four diesel engines.

Teardown revealed extreme main bearing wear and contamination, and that one of the crankshafts had become bent from the forces. Bent cranks are highly unusual in a nine-bearing arrangement.

A year ago, similar crank bearing issues showed up in two other ships delivered, USS Mesa Verde and USS Green Bay, taking them out of service for several months, and making for three out of five ships with basic issues keeping them from being war-ready.

The first two ships built, USS San Antonio and USS New Orleans, had reported no bearing failures. On its first run, however, The San Antonio had been forced into port for an extended period to repair main propulsion lubrication system leaks. The leaks were caused by improper and substandard welds; substandard welds has been a longstanding issue with LPD17 series ships. In 2009, the problem was so bad that every welder at the Pascagula Shipyard was de-certified and had to retrain and recertify.

All of the ships were immediately reinspected after the New York's debacle, and the San Antonio was found to have bearing damage in three of its engines. That leaves only the New Orleans with no history of bearing problems. The San Antonio is now in dry dock, awaiting repairs.

Crank misalignment and the resulting destructive vibrations have apparently been set up in the engines with bearings contaminated by lubricant debris up to 40 microns. While lubricant debris is a universal byproduct of wear and the combustion process, the 40 micron debris was hard enough to damage the bearings and the crank.

Northrup-Grumman is now blaming the shipyard for contaminating the oiling systems as they were being built. They now suggest sloppy work, welding slag, and debris from sandblasting are the culprits. However, stainless steel was reportedly the primary lube contaminant found in the Mesa Verde and Green Bay engine bearings last year. The ships had the lubricant flushed, and the piping replaced between the engine and the main filter strainer.

The New York's bent crankshaft will reportedly keep it in dry dock through this spring.

Yesterday, a large group meeting of everyone involved began in New Orleans. Representatives from the Navy, Fairbanks Morse, Grumman, procurement, to the shipyard on down are involved. They hope to pinpoint the problem, and design and implement a solution.

Meanwhile, repairs to the San Antonio have not begun because its bearing failures are now the focus of a JAGMAN investigation. In December, Fleet Forces Command's Admiral John Harvey ordered a Manual of the Judge Advocate General investigation (JAGMAN). The investigation is led by the Navy's Chief Engineer, Rear Admiral Tom Eccles.