United States 1934 Boris SERGIEVSKY Giant Sikorsky S.42 Pilot Signed Record Flight Cover

5c postal stationery cover, postmarked with Bridgeport duplex (Apr 27), with violet cachet of the Worlds Altitude Record / Seaplane / CAT With 2000 & 5000 / Kilo Load, signed "Boris Sergievsky" in black, with signature of N.A.A. Observer below, unaddressed, a pleasing cover signed by this WWI Flying Ace of Russia and subsequent Test Pilot.