# NTSB DCA22LA179: Boeing 767-332, N181DN, New York, NY, July 7, 2022

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Class 4 · Limited · Final report
- Date: July 7, 2022, 17:30 UTC
- Place: New York, NY
- Location: 40.7143° N, 74.0060° W: Placed by OpenAirDocs: center of New York, NY, within about 10 miles (OpenAirDocs)
- NTSB coordinates: 56.112671, -46.145325, outside the stated state
- Nearby events: https://openairdocs.org/map.md?lat=40.7143&lon=-74.0060&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333)
- Highest injury: No injuries
- Injuries: 233 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Major Investigations Division
- Parties: Delta Air Lines, Inc., DALPA - Accident Analysis and Prevention, Boeing Air Safety Investigation
- NTSB case key (mKey): 105738
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA22LA179
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105738/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105738
- Page: https://openairdocs.org/ntsb/DCA22LA179

## Probable cause

The failure of maintenance personnel to close the drain mast heater circuit breakers which resulted in the formation of ice in the forward drain mast, an improper flow of wastewater into the main landing gear wheel well, and the formation of ice on one or more aileron system components.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel; cases with it: [Boeing 767-332, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=1385101), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md)
- [Fluids: water](https://openairdocs.org/ntsb-findings/01071030): Aircraft › Fluids/misc hardware · Fluid management; cases with it: [Boeing 767-332, 1 case](https://openairdocs.org/ntsb-findings/01071030/cases.md?model=1385101), [All aircraft, 13 cases](https://openairdocs.org/ntsb-findings/01071030/cases.md)
- [Temp/humidity/pressure: low temperature](https://openairdocs.org/ntsb-findings/03031010): Environmental issues › Conditions/weather/phenomena · Effect on equipment; cases with it: [Boeing 767-332, 1 case](https://openairdocs.org/ntsb-findings/03031010/cases.md?model=1385101), [All aircraft, 8 cases](https://openairdocs.org/ntsb-findings/03031010/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute-cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Boeing 767-332, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=1385101), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md)

## Analysis

The flight crew of Delta Air Lines Flight 211reported that they experienced roll control difficulties after being informed of a water leak emanating from the two mid cabin lavatories while enroute from the Václav Havel Prague Airport (PRG), Prague, Czechia to the John F Kennedy International Airport (JFK), New York, New York. The event flight was a Line Check flight flown by two complete crews, each consisting of a captain and a first officer (FO). The flight crew who was flying at the time of the event indicated that a flight attendant called and informed them of water leaking from the two mid cabin lavatories. The flight crew who was not flying at the time confirmed that one lavatory was leaking water from under the lower right side of the toilet onto the floor; the water supply was subsequently shut off and the lavatory was locked to prevent further use. The other lavatory was leaking water from on top of the filter canister under the sink; the water supply to the sink was subsequently shut off and the lavatory was left open for toilet use only. The crew cleaned up as much excess water from the floor as possible. The FO who was the pilot flying during the event stated that shortly after the water leak was reported, an AUTOPILOT caution message was displayed on the engine indicating and crew alerting system (EICAS) screen, along with an audible annunciation. The FO disengaged and reengaged the autopilot several times, however the caution messages, and audible indication persisted, and the aircraft made no lateral course corrections. The FO stated that he then disengaged the autopilot and attempted to make the course corrections manually; however, he was unable to move his control wheel to the left more than a couple of degrees of deflection and was thus unable to input the needed corrections. He then transferred control of the airplane to the captain, who confirmed the FO’s findings of minimal control to the left about the longitudinal axis of the airplane. The FO stated that a “Jammed or Restricted Flight Controls” procedure was performed, and, in coordination with dispatch and maintenance control, it was determined that frozen water was a suspected cause due to the multiple water leaks. The flight crew declared an emergency and was given clearance to descend to 9,000 ft where the temperature was above freezing. As the airplane descended through 12,000 ft, a minor “jolt” was felt by the flight crew. After this, the control wheel operated normally, and the flight continued to and landed safely at JFK. There were no injuries to the 233 passengers and crew onboard the airplane. A review of flight data by Boeing revealed evidence of a temporary restriction in the lateral control system, starting shortly before the initial disconnect of the center autopilot. The evidence of a restriction was apparent in both automatic and manual flight and continued until shortly after the descent began from flight level (FL) 360. During the period of restrictedmovement, the captain’s control wheel showed a restriction at approximately 7 degrees of deflection to the left. Boeing indicated that the 767 lateral flight control system is designed to allow for the override of a restriction in either the captain’s or FO’s flight controls by applying a breakout force to the control wheel on the opposite side. Boeing’s review of the flight data did not find evidence that the airplane lost the ability for an override to take place. The FO’s control wheel position, and control wheel forces for both wheels, is not recorded on the flight data recorder (FDR). The FDR data and statements by the flight crew on the incident flight were inconclusive about the total force input into the flight control system during the event. According to Delta Air Lines, during corrective action after the subject event, the forward and aft lavatory drain mast heater circuit breakers (CBs), located in the electronic equipment bay, were found open. Although there were no current or previous maintenance write-ups on these heaters, Delta removed and replaced them as a precaution. Subsequent testing found the heater elements for the forward drain mast functioned normally. Delta Air Lines reported that before the subject event, this airplane was out of service for maintenance which required pulling the forward and aft lavatory drain mast heater CB’s. It is possible that these CBs were inadvertently left open when the airplane was returned to service on June 23, 2022. Due to the open drain mast heater CBs, it is likely that ice formed in the forward drain mast, allowing drain water from all equipment routed to the forward drain mast to back up in the lines until it leaked outside of the drain system plumbing. The water likely traveled into and drained through the canted pressure bulkhead in the vicinity of aileron control system components located within the main landing gear wheel well. The water likely froze on one or more of the components which led to the pilots’ limited control of the ailerons. Boeing could not identify a location in the roll flight control system where ice formation could restrict both the left and right ailerons if the control wheel breakout was activated.

## Aircraft

- Registration: [N181DN](https://openairdocs.org/deregistered/N181DN-2025-02-03), registration cancelled 2025-02-03, S/N 25986, built 1992 (OpenAirDocs)
- Reported make and model: BOEING 767-332
- Registry model: [Boeing 767-332](https://openairdocs.org/model/boeing-767-332) (registry code 1385101) (OpenAirDocs)
- Registry engine: [Pratt & Whitney PW4000 series](https://openairdocs.org/engine/pratt-whitney-pw4000-series) (registry code 52119, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 25986
- Year built: 1992
- Airframe hours: 131342
- Engines: P&W PW4000 SER 60000 lbs thrust turbo jet; P&W PW4000 SER 60000 lbs thrust turbo jet
- Damage: No damage
- Flight: Part 121
- Operator: Delta Air Lines Inc
- Registered owner: Delta Air Lines Inc
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, July 7, 2022
- Departed: PRG, Prague, OF
- Destination: JFK, New York, NY
- Flight plan: IFR
- Equipment: Electronic flight bag or handheld device, Electronic multifunction display, Electronic primary flight display, Auto-pilot, Onboard weather, Stall warning system, ADS-B, Angle of attack indicator

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Check pilot; age 58; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, unknown; seat: left; flight hours: 10,165 total, 3,449 in this make and model, 165 in the last 90 days, 0 in the last 24 hours
- Pilot; age 29; injuries: none; airline transport, private, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, unknown; last flight review May 21, 2022; seat: right; flight hours: 753 total, 189 in the last 90 days, 0 in the last 24 hours

## Weather

- Conditions: Not reported

## Docket (3 files)

The files NTSB released with the investigation on April 20, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105738. 2.7 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14805992&FileExtension=pdf&FileName=DCA22LA176%206120_Final_Redacted-Rel.pdf
- Flight crew statements (item 2, PDF, 8 pages, 217 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14807290&FileExtension=pdf&FileName=Flight%20Crew%20Statements%20Redacted-Rel.pdf
- Flight crew supplemental statements (item 3, PDF, 9 pages, 349 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14807093&FileExtension=pdf&FileName=Flight%20Crew%20Supplemental%20Statement_Redacted-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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