[Congressional Record Volume 140, Number 90 (Wednesday, July 13, 1994)]
[Senate]
[Page S]
From the Congressional Record Online through the Government Printing Office [www.gpo.gov]


[Congressional Record: July 13, 1994]
From the Congressional Record Online via GPO Access [wais.access.gpo.gov]

 
                         ADDITIONAL STATEMENTS

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                       PROBLEMS HIT F-22 FIGHTER

  Mr. D'AMATO. Mr. President, first the fuselage. Now the 
engine. Next the avionics. Think I am talking about the B-1B? Nope. F-
22.
  I ask that an article that appeared in the May 31, 1994 edition of 
Defense Week, ``Excess Engine `Vibration' Problems Hit F-22 Fighter,'' 
be printed in the Record at the end of my remarks.
  The article follows.

                 [From the Defense Week, May 31, 1994]

          Excess Engine `Vibration' Problems Hit -F-22 Fighter

                           (By Tony Capaccio)

       Excessive, unanticipated vibrations inside the turbine 
     engine of the Air Force's newest fighter have forced the 
     United Technologies Corp.'s Pratt & Whitney unit to redesign 
     the powerplant, according to internal service documents 
     obtained by Defense Week.
       Redesign of the F-22's F119-PW-100 engine will cost the Air 
     Force at least $179 million, according to program office 
     documents.
       The excessive ``vibrational stress,'' or excitation, within 
     the turbine ``is the most serious problem that exists today 
     because it restricts uninhibited engine operation,'' said the 
     final report of a Air Force-commissioned independent review 
     team. It was dated Feb. 8.
       The review team was chaired by William Heiser, an Air Force 
     Academy professor of aeronautics.
       The engine issue represents the most serious technical 
     problem emerging to date in the ongoing 10-year engineering 
     manufacturing and development test phase. The $71 billion F-
     22 program is the second most expensive in the Pentagon 
     procurement pipeline and a potential target of lawmakers 
     hoping to cut the defense budget.
       Pratt & Whitney spokesman Bob Carroll declined comment, 
     referring questions to the Air Force.
       Heiser praised Pratt & Whitney's Government Engines & Space 
     propulsion division for its cooperation. ``We believe that 
     they agree with our findings and recommendations and are 
     ready to act on them,'' he wrote.
       News of the heretofore unpublicized engine problem comes as 
     the Senate Armed Services Committee reviews a recommendation 
     by the General Accounting Office to delay by seven years 
     initial fielding of the jet until 2010 for budget savings.
       The GAO recommendation was driven largely by information 
     suggesting the F-15 could handle any new aircraft threats 
     emerging in that timeframe and not out of any major technical 
     concerns. At $164 million per aircraft, the F-22 is being 
     sold largely on its hoped-for superior performance, increased 
     ranges and improved reliability, all of which are threatened 
     by the engine problem. ``The nature and number of problems 
     being experienced by the P&W F119 are not excessive for a 
     highly sophisticated new centerline aircraft at this stage of 
     development,'' said the review team report.
       ``Major advances in propulsion performance necessarily 
     involve pushing back many technological barriers,'' said the 
     report. ``Nevertheless, the sum of our observations leads 
     directly to our principle conclusion that the pace of the P&W 
     F119 program must be significantly accelerated in order to 
     insure that acceptable versions of the engine are available 
     for flight test and production.''
       ``Taken together, the magnitude of the remaining challenges 
     and shortness of the remaining time (about 18 months are 
     needed to design and manufacture a new turbine) require a 
     revitalized, aggressive approach if the desired goals are to 
     be reached,'' said the report.
       The review team concluded: ``This is a crucial moment for 
     the F-22 system program office to conduct a top-down 
     evaluation of aircraft/engine systems performance in order to 
     assess the impact of probable deficiencies on mission 
     requirements and on F119 engine specifications and 
     priorities.''
       ``New tradeoffs between range, payload, durability and cost 
     must be carried out. This assessment will only become more 
     difficult as major milestones approach and available options 
     become more limited,'' it said.
       ``This is a big problem,'' said a Pentagon official very 
     familiar with the issue. ``If we don't fix any of these 
     problems we can't make our range requirements in terms of 
     fuel efficiency and can't make our reliability 
     requirements,'' he said.
       But given the aircraft's carefully crafted test program, 
     the F-22 development team has time to solve the vexing 
     problems because first flight of a production model F119 is 
     scheduled for 1996.
       The team also warned that, given ``major'' configuration 
     changes and unanticipated development problems, there is a 
     serious shortage of ground test engines for remaining F119 
     development.
       ``Even though there is enough reason to believe that the 
     overall F119 program will require less than half the engines 
     and significantly fewer ground test hours that its 
     predecessors (because of extensive prototype testing and 
     modern analytical methods), there are clear indications that 
     the current numbers are inadequate,'' said the report.
       Among the indications, actual engine test hours compared 
     with planned hours by December 1993 were 577 versus 900. 
     ``The gap is not projected to close for at least two years. 
     There are no back-up engines available for unanticipated 
     future additional testing or to replace one that breaks,'' 
     the report said.
       Known in engineering parlance as ``76E excitation,'' the 
     vibration problem ``not only prevents the timely acquisition 
     of essential ground test data and places some engines at risk 
     but remains a potential safety-of-flight issue for the 
     initial flight release engines until conclusively 
     eliminated,'' said the report.
       ``The 76E problem must be pursued with rigor now,'' wrote 
     the team. The team ``strongly supports the near term effort 
     by P&W,'' it said. [Emphasis in the original.]
       Heiser wrote Feb. 8 to Lt. Gen. Richard Hawley, Air Force 
     principal deputy for acquisition: ``The most important 
     conclusion reached by the [team] is that the pace of the P&W 
     F119 development program must be significantly accelerated 
     relative to that of the previous year in order to insure that 
     acceptable versions of the engine are available in time for 
     flight testing and production,''
       Hawley through a spokeswoman said the Air Force was already 
     planning to redesign the F-22 turbine to increase its fuel 
     efficiency. ``Our biggest [engine] challenge so far is 
     subsonic cruise thrust specific fuel consumption . . . The 
     Air Force knew that the cause of the subsonic fuel 
     consumption shortfall was the turbine.''
       The independent review team validated the Air Force 
     approach, Hawley said. ``In their review summary the [team] 
     noted the aggressive goals for the engine but also noted that 
     the problems encountered were not uncommon for an engine 
     development program at this stage.''
       Hawley's statement failed to mention the far more important 
     issue of excess vibrations.
       The report said the company's engine workforce has 
     ``adequate competence and capacity available for at least one 
     major effort of this sort, provided that they apply it 
     diligently,'' said the report.
       ``Nevertheless, we are anxious about the apparent shortage 
     of experienced aerodynamic designers of highly loaded single 
     stage turbines of the type presented by the F119. We base our 
     concern on the lack of P&W experience with production 
     turbines of this class as well as their reductions in 
     strength in this area.''
       These caveats aside, the team concluded P&W ``is sincerely 
     dedicated'' to a successful development program. ``But they 
     will have to persevere in order to keep the necessary quality 
     and quantity of technical personnel involved.'' The review 
     team concluded that both high and low pressure turbines 
     ``fall far short of their [fuel] efficiency goals. One can 
     see that the shortfall is caused by excessive blade tip 
     clearance and seal leakages and poor airfoil aerodynamics.''
       ``Engine development issues remain a high priority,'' the 
     F-22 system program office wrote in a quarterly program 
     review dated March 24.
       ``The engine has experienced fuel consumption 
     inefficiencies and a durability shortfall in the turbine 
     section. Our initial approach to correct these issues has 
     been reviewed and agreed to be an executive independent 
     review team.'' said the assessment. ``These approaches focus 
     on minimizing blade vibratory stress and tightening blade 
     clearances.''
       The redesign options will be explored in June during a 
     turbine redesign ``critical design review,'' sources said. 
     ``You've got very, very high supersonic air that is exciting 
     the blade twice and it shouldn't be,'' said a Pentagon 
     official familiar with the F-22 program.
       ``Air is entering so fast it is hitting the blade at one 
     angle and bouncing off and, hitting the next blade at a 
     different angle,'' the official said.
       ``It is `excited' in a way it wasn't meant to be excited,'' 
     he said. ``That will shorten the life of the turbine and 
     that's bad. While we are fixing that problem we are going to 
     try to make the whole thing more fuel efficient.''
       The redesign will focus on the turbine section looking at 
     whether Pratt & Whitney must change the blade's aerodynamic 
     shape or add blades.

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