By Rita Hess, USAEC ContractorMarch 6, 2018
The CH-47 Chinook is a twin-engine, tandem rotor, heavy lift helicopter. A true workhorse that was designed and produced in the early 1960s, this aircraft is the Army's only heavy-lift cargo helicopter. Recent changes to a "Block II" configuration include a more efficient drivetrain, new swept-tip rotor blades, and a strengthened fuselage that allows for heavier payloads. Six fuel tanks are reduced to two, allowing the Block II to carry more fuel while losing weight.
Changes of this magnitude don't just happen without careful oversight, however. The System Safety Environmental Working Group (SSEWG) is well equipped for the job, as evidenced by its recent U.S. Secretary of Defense Environmental Award for Excellence in Weapons System Acquisition. The group analyzes and tracks environmental, safety, and occupational health (ESOH) issues associated with Block II; they also establish responsibilities, track progress, and resolve open issues.
"It's critical to the Block II upgrade that we integrate ESOH mitigation efforts early in the acquisition process to avoid program delays and high costs associated with late identification of hazards and risks," said Col. Greg Fortier, Program Executive Office, Aviation's Cargo Helicopters Project Manager. "Addressing ESOH issues throughout the program not only reduces those risks to the aircraft user and the maintainer, it also reduces the burden on Army installations where the aircraft will be fielded through reduced environmental risks and liability."
The PEO, Aviation Cargo Helicopter Project Safety Manager chairs the SSEWG, whose members include technical and managerial representation across functional areas; equipment manufacturers; others from outside the aviation acquisition community, such as the Army Aviation Logistics Center and Research Development and Engineering Command; and a user representative--in this case, the Combat Developer in the Army Aviation Center for Excellence.
The SSEWG achieves its goals by meticulously logging safety hazards and tracking resolution actions. The group oversees the contractor pollution prevention programs, tracks projects that eliminate hazardous material (hazmat) in the aircraft design, recommends environmental compliance measures, and provides recommendations for establishing or revising system safety requirements.
Members communicate often and meet semiannually to address key issues including environmental risks, regulations, policies, and potential compliance issues. Thus far, the SSEWG has successfully communicated, implemented, and executed ESOH requirements to the team, as well as discussed lessons learned and applied across all the supporting disciplines.
Using Department of Defense guidance and industry standards, the group also initiated efforts to eliminate, reduce, or mitigate hazmat use by focusing on these materials early in system design and material selection. Periodic reports identified all hazmat required for production, operation, repair, maintenance, storage, transportation, or disposal of the aircraft. Boeing (the contractor for the initial Block II upgrades) has an active pollution prevention program. Detailed documentation affiliated with hazmats shows the Block II Program introduced no new hazmat materials, processes, or disposal activities with the CH-47F and has reduced hex chrome and other materials targeted for elimination.
Several technical accomplishments reflected the tenacity of the program office. For example, rigorous laboratory tests and data analysis showed that Tagnite� surface treatment met or exceeded all requirements necessary to replace the chromate surface treatments for cast magnesium surfaces. The Project Manager for Cargo Helicopters thus adopted an advanced Tagnite� coating system, which reduces the amount of chromium on the CH-47 aircraft and will reduce parts rejection. In addition, a different product was qualified to replace the previous drive system resin coating.
The CH-47F Block II Program includes composite rotor blades that provide greater lift capacity. This meant the horizontal hinge pin had to be redesigned and the material was changed. Also, the sleeves (bearing inner races) were strengthened by increasing their thickness and using a low-carbon, carburizing steel. This required qualification of a different thermal spray coating, which reduces wear. In addition, the pin and bearing are compatible with all the F and G models of the CH-47 aircraft.
Finally, the Project Manager for Cargo Helicopters has taken a leading role in replacing halon in engine compartment fire suppression systems. Halon 1301 is a Class I ozone-depleting substance (ODS) banned from production in 1994. CH SSEWG has pursued multiple replacement efforts over the last 25 years. A new hand-held fire extinguisher that uses sodium bicarbonate and the hydrofluorocarbon HFC-227ea instead was developed and qualified by the Aviation Ground Support Equipment (AGSE) Product Office within the Program Executive Office for Aviation. The new extinguisher may be fielded on the CH-47F Block II with successful completion of testing.
In summary, the CH SSEWG diligently ensured a safe and environmentally acceptable design, including the production, fielding, and operation of Block II aircraft with minimal effect on mission effectiveness and program cost.