Date: 201306
Local time of day: 1801-2400
Location: LEX.TRACON, KY
Flight conditions: IMC
Weather elements / visibility: Turbulence; Rain; Thunderstorm
Aircraft: PA-23-250 Aztec
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Flight phase: Cruise
Airspace: Class E LEX
ATC / advisory: TRACON LEX
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Other / Unknown
Anomaly: ATC Issue All Types
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: A PA-23 was on a vector for the LOC Runway 25 approach to FFT; direct to FFT to keep aircraft west of precipitation. RADAR depicted heavy to extreme precipitation between LEX and FFT; but no precipitation was observed outside 20 NM of LEX. Aircraft was assigned a 020 heading to place him over the top of FFT for a right downwind to the final and clear of the precipitation. After I was relieved from position and during the overlap; I stayed in the TRACON to help re-coordinate multiple deviations and a satellite departure. Later the aircraft changed course and lost a significant amount of altitude; to approximately 1;400-1;600 MSL (400-600 AGL). Our MVA in that area is 2;500 FT. We later learned that due to a previous equipment issue earlier in the day; our RADAR weather presentation was only showing to approximately 12 NM from the ASR antenna. No one at LEX was aware of this issue and as a result; I had issued a vector to this aircraft directly into a severe thunderstorm with heavy to extreme precipitation. SDF TRACON later confirmed the location and intensity of the weather area. AOCC later advised that no Maintenance Personnel would be sent to correct this issue due to the sequester. There are continuing severe thunderstorms in the area impacting operations at LEX and we are unable to provide any sort of weather advisories to aircraft operating outside of a 15 NM-R of the LEX ASR.Weather RADAR is essential to the safety of aircraft. It is even more critical during periods of convective activity. The lack of accurate weather RADAR information nearly led to the loss of this aircraft and its crew. Further; this is an entirely preventable occurrence. The fact that a known and reported safety critical component of the NAS will not be fixed ASAP due to budget issues is almost criminal. Critical safety issues must be addressed when reported. This problem should be corrected immediately and the controllers/FLMs and ATM should have been advised of this equipment limitation/failure. I'm not sure if the limited radius of weather presentation is a default setting following an equipment reset/failure; but if so; it should be corrected to show weather information to the full operational range of the ASR 11. Further suggest a feed from FFT's ASOS to the LEX IDS system. Such information would have indicated a RADAR/equipment issue.




Synopsis: LEX Controller described a possible vector into weather due to equipment problems with no maintenance available to correct the problem; allegedly due to budget constraints.