August 9, 1999
Boeing Troop Helicopters Grounded For Checks
The Army said Monday it had grounded its 466 CH-47 ``Chinook'' troop helicopters made by Boeing Co . and advised other militaries to halt flights worldwide after a crack was found in an engine gear of a British CH-47.
The twin-engine workhorse Chinook, first introduced in the early 1960s and updated several times
since, can carry 33 fully-equipped soldiers and a crew of three.
Army officials said the halt for safety checks was ordered late Friday and that Boeing would help inspect transmission gear assemblies, including those in more than 300 CH-47s bought by the militaries of other countries. The grounding affects only CH-47D and derivative models that have entered service since 1982.
Officials said the ``prudent'' stand-down was made because failure of the transmission gear could have catastrophic consequences during flight. The Army stressed that the gear problem had not caused any accidents, however.
About 10 countries outside the United States fly CH-47s including Britain, Egypt, Greece and Singapore.
The cracked engine transmission gear was found recently in a CH-47 second stage planetary gear assembly during a routine check by the British Royal Air Force.
A subsequent Boeing investigation discovered three more cracked gear assemblies in the company's factory inventory.
Jack Satterfield, a Boeing spokesman, said the worldwide fleet was grounded until the company can determine exactly which helicopters contain the suspect gear assembly made by an unidentified supplier.
Once Boeing determines exactly which gear assembly units are affected, it will recommend that those helicopters be returned to a major maintenance base, where their transmissions can be taken apart and inspected.
``If they don't contain parts from this manufacturer ... what we're going to need to do is evaluate those and probably clear those people to return to flight status,'' Satterfield said.
He said Boeing was working with the supplier to determine how many gear assembly units were in the affected production lot, a process that will take several days.
In addition to the gears in the lot in question, Boeing was investigating the condition of gears in other manufactured lots, the Army said.
``We want to make a very thorough check to make sure that the problem is addressed,'' said Dan O'Boyle, a spokesman at the U.S. Army's Program Executive Office for Aviation at Redstone Arsenal in Alabama.
Army Grounds Fleet of Helicopters
The Army announced Monday it was temporarily grounding its entire fleet of CH-47 Chinook
transport helicopters after a crack was found in a transmission gear in one being used by the British Royal Air Force.
``The fleet is grounded. It's a precautionary measure,'' said an Army spokeswoman, Nancy Ray.
She said that 466 helicopters in the Army fleet were involved in the temporary grounding.
``In an overhaul, the Royal Air Force discovered a cracked gear. That gear has been traced diligently,'' Ray said. She said Boeing was working with the Army Aviation Center to see if the problem affected any of the Army Chinooks.
The twin-rotored Chinook helicopter is the military's medium tactical heavy-lift transport.
Meanwhile, the British Ministry of Defense said Monday that it has grounded its fleet of Royal Air Force Chinooks also pending safety checks.
The Boeing Co., which manufactures the helicopter at its Philadelphia plant, requested the suspension of flights by about 20 operators around the world to allow inspection of their transmissions, said company spokesman Jack Satterfield.
Boeing's subsidiary, Boeing Precision Gear in Chicago, manufactured the type of gear used in the aircraft, Satterfield said.
``All the models should be suspending flight operations pending a check of records to determine if the aircraft contained gears from the suspect production lines,'' he said.
The US Army has the largest fleet of Chinooks. Between 300 to 400 Chinooks are used in other countries, including Australia, Argentina, Spain, Italy, Greece, Morocco, Egypt, Taiwan and Japan, Satterfield said.
August 27, 1999
Army Allow Helicopters To Fly
WASHINGTON (AP) -The Army announced Friday that half its fleet of CH-47 Chinook transport helicopters will return to limited flight while tests continue of suspect transmission gears.
The Army grounded its entire fleet of 466 Chinooks on Aug. 9 after the discovery of a cracked transmission gear during an aircraft overhaul.
Army units continue to work with the Boeing Co., which manufactures the helicopter in its Philadelphia plant, to locate all gears of the suspect type and design, the Army said.
No accidents or mishaps have been attributed to cracked gears.
The Army said it hoped to get the entire fleet back into full flight operations as soon as possible.
August 30, 1999
Boeing Developing Low Maintenance Rotor Hub for CH-47 Chinook
PHILADELPHIA ( Boeing Company Press Release) -
The Boeing Company has signed a contract with the US Army to launch development of a new low maintenance rotor hub that will provide major cost and readiness benefits for the CH-47 Chinook, already the world's most efficient and versatile heavy-lift helicopter.
The current CH-47D rotor hub was designed with significant growth capability but contains 400 parts in the hub system assembly, including nine critical bearings that require lubrication. These bearings contain drain points that allow lubricants to escape, requiring inspection, repair and replacement of seals and other parts while creating additional support and operating costs.
The new technology design, used on other advanced rotorcraft such as the Boeing
AH-64D Apache Longbow and the Boeing Sikorsky
RAH-66 Comanche armed reconnaissance helicopter, replaces lubricated or ``wet'' bearings with elastomeric ``dry'' bearings that require no additional lubrication. The elastomeric rotor hub eliminates at least 10 days of unscheduled maintenance each year for every Chinook fielded with the new system. This saving translates into a significant readiness rate increase.
The new rotor design also will provide a longer fatigue life of 4,500 hours, 75 percent fewer parts and a 70 percent reduction in special maintenance tools. All components can be replaced in the field and will not require depot-level overhaul. The new rotor head will be interchangeable with the existing Chinook hub and will retain the same rotor flight dynamics.
The low maintenance rotor hub program calls for development, testing and installation of the new system over four years. New rotor hubs will be incorporated gradually into the U.S. Army's Chinook fleet, as well as Chinooks operated by the U.S. Special Operations Forces, Army Reserve and U.S. Army National Guard. Estimated operation and support cost savings will exceed $200 million over the next 20 years. The Army also is evaluating inclusion of the low maintenance rotor hub in the CH-47F Improved Cargo Helicopter program, and will be incorporated into the CH-47SD international Chinook.
The low maintenance rotor hub program involves a number of innovative approaches to system development. The United Kingdom is preparing a Memorandum of Understanding that will permit its participation as a partner in the program. The British Royal Air Force operates the second largest fleet of Chinooks. Its participation in this program will provide the same operation and support cost savings per aircraft estimated by the U.S. Army.
The proposal activities also have utilized an innovative contracting technique in support of acquisition reform, called Alpha contracting. Alpha contracting emphasizes a close working relationship between the contractor and government customer to clearly define program requirements and prepare a concurrent, mutually agreed to statement of work and proposal pricing package. From solicitation development, through proposal preparation, to evaluation, negotiation and award, Alpha contracting relies on a team approach to concurrently develop a scope of work, program price and execution plan.
The Boeing Company in Philadelphia manufactures and develops world-class rotorcraft for the U.S. armed forces and military customers around the globe. Its products include the CH-47 Chinook, the fuselage of the AH-64D Apache Longbow, and, with Bell Helicopter Textron, the
V-22 Osprey tiltrotor aircraft. Boeing also is developing the RAH-66 Comanche armed
reconnaissance helicopter with Sikorsky Aircraft.