Pitot Tubes

Editorial Staff

Tuesday, April 20, 2021 at 09:33 AM ET

Verified

Key Takeaways:

Aircraft experienced a range of pitot system issues, including incorrect part installation, physical damage (cracked risers, fractured tubing), obstructions, and leaks.
These failures led to critical flight instrument problems such as inaccurate or disagreeing airspeed indications, altitude discrepancies, and in one case, a total loss of airspeed causing a secondary failure of an attitude/direction indicator.
Problems were discovered through various means, including scheduled maintenance checks and in-flight observation, with some incidents highlighting difficult-to-detect damage or suspected design flaws requiring redesign.

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Beechcraft A200 King Air

Mismatched Pitot Tubes

During altimeter and pitot static system recertification, the technician observed the left pitot tube was incorrect and was actually a right one. Further investigation revealed the p/n was misidentified as a left pitot tube (p/n PH502-3) when the drain hole and embossed “top” mark were consistent with a right pitot tube (p/n PH502-5).

Part total time: 702.0 hours

Cessna 340A

Cracked Pitot Tube Riser

While performing scheduled static system tests, excessive pitot leak was discovered and isolated to the forward nose area. On pitot tube (p/n AN58121) removal, the riser was found to be cracked approximately 50 percent of its circumference. Replaced the tube with a serviceable unit and the system tested satisfactorily. Due to the pitot tube riser’s location—below the nose avionics shelf and ahead of an air conditioner condensing coil—the cracked area would not have been visible during a routine visual inspection.

Part total time: Unknown

Cessna 560XL Citation Excel

Airspeed Disagreement

Both pilots PFDs displayed an amber IAS message after passing through 160 KIAS, with pilot’s IAS showing 160, F/O’s IAS indicating 166 and the standby indicating 167. On accelerating to 200 KIAS, the split increased to about nine knots, with right side showing faster than left. On inspecting the pitot tubes, the technician found a small rock in pilot-side pitot. System was purged and leak check revealed pilot’s static system leak at drain. Removed and replaced O-ring and returned aircraft to service.

Part total time: Unknown

Robinson R44 Raven II

Fractured Pitot Tube

Tubing on back of heated pitot tube fractured and came off for the second time, causing total loss of airspeed indication. Loss of airspeed also caused Aspen Evolution EFD1000H to fail in direction and attitude. Heated pitot tube from Robinson fractured prematurely for second time and needs redesign. Aspen unit should not lose direction and attitude indicator when only losing airspeed from pitot.

Part total time: 2837.0 hours

Tecnam P2012

Leaking Pitot Tubes

During cruise flight, PFD 1 was indicating eight knots faster than PFD 2 and PFD 2 was indicating 100 feet higher than PFD 1. Both pitot tubes were found to be leaking at the pitot tube shell. The pitot tubes were replaced with new assemblies, and the aircraft was returned to service. The pitot tube part numbers are: 212-34-10-0015-001 (left) and 212-34-10-0015-002 (right).

Part total time: 47.0 hours