Cessna 402/402C/B379 Businessliner/Utiliner
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 300; Flight Crew Total 23750; Flight Crew Type 6000
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Weather; Environment - Non Weather Related
[While] being vectored for the ILS Runway 15R BOS; cleared from 4000 ft to 3000 ft. Encountered windshear/wake turbulence and aircraft lost 700 ft. ATC queried altitude and [I] leveled back to 3000 ft.
C402 pilot reported encountering wake turbulence and/or windshear on approach to BOS that resulted in a loss of 700 ft.