Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain McDonnell Douglas transport category airplanes. This proposed AD would require doing repetitive detailed inspections for accumulation of debris (blockage) of the drain holes of the pitot tubes, and cleaning if any evidence of debris is found. This proposed AD is prompted by reports of blocked drain holes of the pitot tubes. We are proposing this AD to prevent blocked drain holes of the pitot tubes, which could result in the accumulation of water in the pitot-static system and consequent failure of that system. Failure of the pitot-static system could result in erroneous airspeed indications in the cockpit and consequent loss of airspeed control.