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UTTAS (Utility Tactical Transport Aircraft System)

The Utility Tactical Transport Aircraft System (UTTAS) program (1972-1978) was designed for troop transport, command and control, MedEvac, and reconnaissance, to replace the UH-1 Series Huey in the combat assault role. In the 1970s the Army's "Big Five" procurementn programs were the Patriot antiaircraft missile, the XM-1 tank, the AAH armed helicopter, the MICV armored fighting vehicle, and the UTTAS transport helicopter.

This aircraft would be the Army's first true squad assault helicopter and it was designed to transport troops and equipment into combat, resupply these troops while in combat, and perform associated functions of aeromedical evacuation, repositioning of reserves, and other combat support missions. An Army objective for the UTTAS is to achieve increased cost effectiveness through substantially improved maintainability, reliability, survivability, and performance.

By late 1969 the Army was conducting a number of studies involving airmobile operations or helicopter employment. Related studies include the Aerial Reconnaissance and Surveillance Survivability Analysis (ARSSA), the Airmobility in the Mid/High Intensity Environment study (AM/HI), the Family of Army Aircraft Systems study (FAAS-85), the Aviation Organization Requirements for the Army study (AORTA), and the Utility Tactical Transport Aircraft System study (UTTAS). In 1969 the Army initiated two aircraft development programs considered vital to the expanding role of aviation in the Army combat team. These programs, the heavy lift helicopter (HLH) and the utility tactical transport aircraft system (UTTAS), are designed to develop new aircraft systems for introduction into the inventory during the period 1975-80. Both started in the concept formulation phase, in which a written requirement is defined. The HLH program will provide an external load capability for tactical airlift of the majority of the Army's combat vehicles, including the mechanized infantry combat vehicle (see below). The UTTAS program will produce an aircraft to replace the battle-proven UH-1 series. In UTTAS development, emphasis has been placed on improving the maintainability, reliability, and survivability of the assault vehicle, while increasing the troop lift capability to a complete squad plus three crew members.

The UTTAS Concept Formulation efforts produced a decision to initiate development the first time it was considered at the OSD(Office of the Secretary of Defense) level. The case study attempts to supplement the recorded history with the illumination of the many and varied aspects that impinged on and influenced the UTTAS program. With a potential for more than $2 billion worth of business for a depressed industry, the US aerospace industry, the interests in UTTAS were from a very broad base of industry and government. The multi-service utilization of this class of helicopter added the complexities of possible joint development. The Concept Formulation was done very openly with participation from OSD level to Combat Developments Agency. Although delays were experienced, actions were expedited at decision time.

An analysis of the economic benefits of providing crashworthiness improvements within future Army utility helicopters was performed for use in the Cost and Operational Effectiveness Analysis (COEA) for the Utility Tactical Transport Aircraft System (UTTAS). The analysis baseline was all UH-1H major aircraft accidents from January 1972 through December 1975. Major accident rates and losses due to accidents were derived for each COEA candidate aircraft. Losses were projected for a twenty year period of peacetime operation. Projections were derived based on each candidate's design features and the effectiveness of these features under the particular conditions in each UH-1H accident.

The test objective of the maneuvering flying qualities evaluation on the OH-6A, OH-58A, BO-105, and L-286 helicopters in 1971 was to evaluate the suitability of three types of rotor systems (articulated, teetering, and hingeless) to perform the proposed utility tactical transport aircraft system (UTTAS) pull-up and pushover maneuvers. The testing consisted of 41 flights for a total of 22 productive hours. The results obtained during this test established a data base to assess the applicability of the presently stated UTTAS maneuverability requirements. It was determined that present-day rotary-wing aircraft can be tested against the prescribed maneuver criteria with meaningful results. Three flying quality deficiencies were noted, correction of which is mandatory if procurement or envelope expansion is anticipated. There were two shortcomings, correction of which was desirable if procurement or envelope expansion was anticipated.

Following approval of the Utility Tactical Transport Aircraft System (UTTAS) materiel need document, a contract was signed with General Electric Company for the development of the UTTAS power-plant. On March 6, 1972, the General Electric Company was awarded a cost plus-Incentive fee contract to develop, furnish, and support 18 ground test and 56 flight test engines. The number of flight test engines being procured was decreased from 56 to 32 when the flying prototype program was reduced to 3 aircraft per contractor. The reduction in the number of engines needed will result in a decrease to the engine contract of approximately $1,387,000.

In August 1972, the U.S. Army selected the Sikorsky (model S-70) YUH-60A and the Boeing-Vertol (model 237) YUH-61A (1974) as competitors in the Utility Tactical Transport Aircraft System (UTTAS) program. The Boeing Vertol YUH-61A had a four-bladed composite rotor, was powered by the same General Electric T700 engine as the Sikorsky YUH-60A, and could carry 11 troops.

The two airframe contractors, the United Aircraft Corporation (Sikorsky Aircraft Division) and the Boeing Company (Vertol Division), were awarded contracts on August 30, 1972, for competitively developing UTTAS prototypes. After evaluation, which includes a competitive fly-off, the Army will select one of these contractors to produce the UTTAS aircraft. Cost-plus-incentive-fee contracts were awarded to Boeing/Vertol with a target price of $91.3 million and to Sikorsky with a target price of $61.9 million. These contracts are for designing, developing, fabricating, and testing a missioneffective UTTAS. Each contractor is to build three flyable prototypes, one ground test vehicle, and one static test article. Each contract also contained an option for the Army to purchase a maximum of six flyable prototypes if congressional approval was received.

The initial Army plans called for 16 developmental aircraft (one static test article, one ground test vehicle, and six flying prototypes for each contractor). However, the development program was reduced from a 6-flying prototype program to a 3-flying prototype program per contractor, in accordance with Congressional direction. The House Appropriations Committee Report 92-1389, dated September 11, 1972, stipulated that the number of flying prototypes should be reduced to three for each contractor.

Sikorsky's UTTAS design was less complex than Boeing/Vertol's. This simpler design should result in less man-hours per pound to manufacture the prototypes and could also account for some differences in tooling and recurring manufacturing costs. Sikorsky had previously developed and built helicopters of similar size, weight, and rotor configuration which incorporated a number of the same features included in its UTTAS design. These helicopters were more related to the UTTAS design than any previously built by Boeing/Vertol. Boeing/Vertol had proposed features on which they had had little or no experience. Sikorsky had undertaken more independent research and development projects directly relating to its UTTAS design than had Boeing/Vertol. The Army concluded that Sikorsky's history and experience in these areas supported a lower development cost than Boeing/Vertol's.

Experience accumulated in these areas negated the need for many tests by Sikorsky. Also Sikorsky had capitalized major pieces of test equipment which would not be directly chargeable to the UTTAS program, while Boeing/Vertol would charge similar equipment directly. Sikorsky already has test equipment and fixtures which require only minor modifications for the UTTAS program, while Boeing/Vertol requires new test equipment and fixtures. In addition to these differences attributed to the scope of work, the Army's cost estimate for the UTTAS development effort was higher than Sikorsky's proposed cost estimate (which became the target cost in the Sikorsky contract).

During contract negotiations, Sikorsky was given the opportunity to adjust its bid price and, in fact, increased it. The final contract figures were those proposed by Sikorsky. The Sikorsky estimate assumed favorable utilization of previous technology and experience. The Army believed that while Sikorsky's estimate could be achieved under very favorable conditions, a higher development cost was more likely.

Overall, technical risks in developing the UTTAS helicopter were considered moderate. Army officials stated that all the technology exists for this development. The most challenging area and the highest risk item in the program was the requirement to meet reliability and maintainability goals. Project Manager Office officials have stated that above-normal effort was required to meet these goals.

The estimates in the June 30, 1972, SAR were prepared using historical experience with similar aircraft, engineering estimates, and expert opinion. These estimates provide for a normal level of effort for reliability and maintainability. The estimates also contain an additional $55.1 million over and above that included for a normal level of effort to provide for additional contractor effort to meet the reliability and maintainability goals of the UTTAS program.

By the close of fiscal year 1973 the contractors had completed design layouts, released detailed drawings, and subcontracted for long, lead time hardware. Wind tunnel testing, computer simulation of aircraft handling qualities, and building of the static test model, ground test vehicle, and flyable prototypes had begun. Tests of the General Electric T700 engine, which powered the UTTAS, indicated that horsepower output did not meet specifications. Efforts to correct the deficiency, including the redesign of the power turbine, have been started. Congressional action reduced by 50 percent the number of flyable prototypes each contractor may build. As a result the Army expected to fall short of its reliability and maintainability goals for the UTTAS program.

Critical design review of the airframes for the utility tactical transport aircraft (UTTAS) developed by Boeing Vertol and Sikorsky Aircraft was completed in December 1973, while a revised General Electric T-700 engine to power the UTTAS successfully passed its final acceptance tests in March 1974 and delivery began in April.

The Army's fiscal year 1974 research, development, testing, and evaluation (RDT&E) program, as contained in the President's budget request to Congress, was $2,108.7 million. Later the program was amended: $6.2 million was taken away from the utility tactical transport aircraft system (UTTAS), $8.4 million withdrawn from the nuclear munitions program, and $1.1 million added to cover the higher costs of petroleum products. Program and budget decisions by the Office of the Secretary of Defense and the Office of Management and Budget reduced the Army RDT8cE request for fiscal year 1975 to $1,886 million, the amount included in the President's budget request to Congress in January 1974. Because of this reduction, the UTTAS, Safeguard, Site Defense, and SAM-D programs were adjusted, and the Land Warfare Laboratory in Aberdeen, Maryland, was selected for closure as a cost-saving measure.

The estimate for development and acquisition of 1107 hellcopters as of June 30, 1973, was $2,325.7 million. This amount represents a reduction of $18.8 million from the $2,344.5 million estimate reported in the SAR of June 30, 1972. A contemplated stretchout of the production program from eight to ten years ml1 doubtlessly fncrease the estimate for production of $1,913.2 million, stated in FY 1972 escalated dollars. As of June 30,1973, program acquisition unit cost was estimated at $2.08 million. The estimate as reported in the September 30, 1973, SAR was $2,342.7 million, up $17.0 million over the June 30, 1973, SAR. This increase was attributable to contingency funding being held for further reliability and maintainability testing as required to achieve target goals.

The United States Army Aviation Engineering Flight Activity conducted the engineering flight test portion of the Government Competitive Test of the Sikorsky Model YUH-60A utility tactical transport aircraft system (UTTAS) helicopter from 7 April through 17 September 1976. Performance, handling qualities, engine characteristics, and vibration characteristics were evaluated to provide engineering flight test data to the UTTAS Source Selection Evaluation Board for comparison with the UTTAS Request for Proposal, to determine compliance with the applicable paragraphs of the Prime Item Development Specification (PIDS), to provide airworthiness data as a basis for modification/updating of the safety-of-flight release for other Army tests, and to detect and allow for early correction of any aircraft deficiencies or shortcomings.

The YUH-60A was tested at Edwards Air Force Base (elevation 2303 feet), California, and at alternate test site elevations of 425, 4120, and 9500 feet. A total of 162 flights were conducted for a total of 156.7 flight hours. The YUH-60A failed to meet the following performance commitments of the PIDS: primary mission gross weight, hover, single-engine takeoff, vertical climb, forward flight climb service ceiling, cruise airspeeds, single-engine maximum airspeed, the alternate endurance mission, and the 3-hour endurance mission.

An evaluation of the Reliability, Availability, Maintainability and Durability (RAMD) characteristics of the Boeing YUH-61A and the Sikorsky YUH-60A UTTAS candidates was conducted. The evaluation is based on Development Test II (DT II), and Operational Test II (OT II) data. The Boeing and Sikorsky UTTAS candidates' demonstrated RAMD characteristics are compared to each other as well as to the Bell UH-1H and the requirements as stated in the UTTAS Materiel Need (MN) and the Decision Coordinating Paper (DCP).

There were no significant differences in the mean-time-between mission abort estimates of the UTTAS candidates. Both candidates demonstrated a significantly higher mission reliability in OT II as compared to DT II. The estimates of mission reliability during DT II and OT II are considered conservative since they were dependent upon pilot judgment and safety considerations in a prototype test environment. The analysis indicates that in a combat environment both UTTAS candidates could demonstrate a mean-time between- mission abort at least twice as great as the value demonstrated during DT/OT II.

The scheduled, corrective, and total maintenance burden (maintenance man-hours per flight hour) of the UTTAS candidates were evalutated during DT II and the last 200 hours of OT II. The Sikorsky corrective and total maintenance burden in DT II was significantly less than that of Boeing. The scheduled maintenance burden of the Sikorsky UTTAS in DT II was significantly greater than that of Boeing. During the last 200 hours of OT II, however, there was no significant difference in the corrective, scheduled, or total maintenance burden of the two candidates. The Boeing UTTAS demonstrated a slightly higher operational availability than that of Sikorsky during the last 200 hours of OT II, whereas the Sikorsky UTTAS demonstrated a slightly higher value than that of Boeing during DT II. These differences, however, are not significant.

In December 1976 Sikorsky won the competition to produce the UH-60A, subsequently named the Black Hawk. The Sikorsky (S-76) H-76 Eagle was based on technology developed for the UH-60A.

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