Joe, A blockage in the Pitot tube or pitot plumbing will cause the ASI to lag, reading low at times, then high when you slow down. A blockage in the static system will cause the ASI to be erratic, reading both high and low at times as altitude changes. If the ASI is functioning normally, but reading low, that is almost always a leak in the plumbing somewhere between the pitot tube and the instrument. Check your pitot plumbing for loose joints, cracked tubes, or hardened tubing that may not be sealing well anymore.
It is possible that the instrument is failing, but they rarely fail all at once. The instrument typically fails in a gradual manner. -Jeff Scott Los Alamos, NM ? ? My airspeed indicator is suddenly inaccurate. ?It reads 32 mph rather than 55 mph. ?What would cause a sudden change? ?I have found no blockage in my ram air or static lines. ?The pitot tube alignment is normal. ?I haven't added a static drain point yet. ?Can the instrument have gone bad and can I fix it? ?What more can I do?Thank you. Joe Nunley?CW2 US Army RetiredBaker JROTC Instructor?Baker Florida? _______________________________________________
