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B737 pilot crew reported erratic airspeed indications which resulted in executing an rejected takeoff. A mud wasp nest was found in the pitot system.
| Attributes | |
| ACN | 1740194 |
| Time | |
| Date | 202004 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Takeoff |
| Route In Use | Direct |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Airspeed Indicator |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 66 Flight Crew Total 6363 Flight Crew Type 5445 |
| Person 2 | |
| Function | First Officer Pilot Not Flying |
| Qualification | Flight Crew Instrument Flight Crew Private Flight Crew Multiengine Flight Crew Commercial |
| Experience | Flight Crew Last 90 Days 150 Flight Crew Total 4900 Flight Crew Type 4900 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy |
Narrative:
We were conducting a maintenance ferry flight to ZZZ1 to place the aircraft in storage. The aircraft was secured; properly prepared and [the] crew [was] briefed in accordance with SOP for this operation. On takeoff roll; at the required 100 kts. Call by the pilot monitoring; the airspeed indicators were observed to be in disagreement by the first officer; the obvious indication was amber airspeed disagree messages on both pfds. The first officer verbalized 'airspeed disagree' at which time I looked at both indicators; noted the amber messages and observed my indicator to be approximately 15 kts. Higher. My hand was still on the throttles and the aircraft was accelerating rapidly due to the light gross weight. I honestly don't remember if the reject was commenced above V1 because of the airspeed differential; however; I elected to reject the takeoff as the safest course of action. I quickly reasoned the situation might progressively get worse airborne and cause more problems; so I kept the aircraft on the ground.I announced 'reject' and the first officer made a call to tower. We cleared the runway; stopped the aircraft on the taxiway and the rejected takeoff qrc/qrg were conducted in accordance with FM procedures. Crew had a conversation about the event and felt the aircraft was safe to taxi and informed station maintenance of the occurrence. We were directed to return to our original gate and received ATC clearance to do so. An electronic logbook entry was made; brake cooling charts referenced; and maintenance personnel were briefed. A thorough crew debrief was also conducted. Maintenance conducted an investigation of the pitot tubes and forward electronics compartment. Their suspicions were proved correct when they postulated the event was caused by mud daubers nesting in the pitot tubes. They had indicated we were the 3rd or 4th event that week. Corrective action was taken; and we flew to ZZZ1 uneventfully. I'm assuming our event was enough of a trend to trigger a bulletin from station operations detailing the problem and corrective actions.
Original NASA ASRS Text
Title: B737 pilot crew reported erratic airspeed indications which resulted in executing an RTO. A mud wasp nest was found in the pitot system.
Narrative: We were conducting a maintenance ferry flight to ZZZ1 to place the aircraft in storage. The aircraft was secured; properly prepared and [the] crew [was] briefed in accordance with SOP for this operation. On takeoff roll; at the required 100 kts. call by the Pilot Monitoring; the airspeed indicators were observed to be in disagreement by the First Officer; the obvious indication was amber Airspeed Disagree messages on both PFDs. The First Officer verbalized 'airspeed disagree' at which time I looked at both indicators; noted the amber messages and observed my indicator to be approximately 15 kts. higher. My hand was still on the throttles and the aircraft was accelerating rapidly due to the light gross weight. I honestly don't remember if the reject was commenced above V1 because of the airspeed differential; however; I elected to reject the takeoff as the safest course of action. I quickly reasoned the situation might progressively get worse airborne and cause more problems; so I kept the aircraft on the ground.I announced 'Reject' and the First Officer made a call to Tower. We cleared the runway; stopped the aircraft on the taxiway and the Rejected Takeoff QRC/QRG were conducted in accordance with FM procedures. Crew had a conversation about the event and felt the aircraft was safe to taxi and informed station maintenance of the occurrence. We were directed to return to our original gate and received ATC clearance to do so. An electronic logbook entry was made; brake cooling charts referenced; and maintenance personnel were briefed. A thorough crew debrief was also conducted. Maintenance conducted an investigation of the pitot tubes and forward electronics compartment. Their suspicions were proved correct when they postulated the event was caused by mud daubers nesting in the pitot tubes. They had indicated we were the 3rd or 4th event that week. Corrective action was taken; and we flew to ZZZ1 uneventfully. I'm assuming our event was enough of a trend to trigger a bulletin from station operations detailing the problem and corrective actions.
Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.