# NTSB CEN12LA220: Cirrus Design SR22T, N229TX, Addison, TX, March 23, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 23, 2012, 11:00 local (16:00 UTC) - Place: Addison, TX - Coordinates: 32.968612, -96.836387 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.9686&lon=-96.8364&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi-to runway: Electrical system malf/failure](https://openairdocs.org/ntsb-events/332) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 11, 2014 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, Dallas FSDO, Cirrus Aircraft Corporation - NTSB case key (mKey): 83278 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA220 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83278/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83278 - Page: https://openairdocs.org/ntsb/CEN12LA220 ## Probable cause Maintenance personnel’s improper maintenance, which resulted in the incorrect wiring of the No. 1 alternator and a subsequent electrical system fire during taxi. Contributing to the accident was the airplane manufacturer's inadequate maintenance documentation that did not depict updated electrical system wiring options. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Electrical power system: aC generator-alternator](https://openairdocs.org/ntsb-findings/01022421): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Cirrus Design SR22T, 1 case](https://openairdocs.org/ntsb-findings/01022421/cases.md?model=2130004), [All aircraft, 14 cases](https://openairdocs.org/ntsb-findings/01022421/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cirrus Design SR22T, 3 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=2130004), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) - [Electrical power system: aC generator-alternator](https://openairdocs.org/ntsb-findings/01022421): Aircraft › Aircraft systems · Related maintenance info (probable cause); cases with it: [Cirrus Design SR22T, 1 case](https://openairdocs.org/ntsb-findings/01022421/cases.md?model=2130004), [All aircraft, 14 cases](https://openairdocs.org/ntsb-findings/01022421/cases.md) - [Documentation/record keeping: maintenance records](https://openairdocs.org/ntsb-findings/04033025): Organizational issues › Support/oversight/monitoring · Manufacturer (probable cause); cases with it: [Cirrus Design SR22T, 1 case](https://openairdocs.org/ntsb-findings/04033025/cases.md?model=2130004), [All aircraft, 16 cases](https://openairdocs.org/ntsb-findings/04033025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Cirrus Design SR22T, 2 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=2130004), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Taxi-to runway: Electrical system malf/failure](https://openairdocs.org/ntsb-events/332) (defining event); cases with it: [Cirrus Design SR22T, 1 case](https://openairdocs.org/ntsb-events/332/sequence.md?model=2130004), [All aircraft, 182 cases](https://openairdocs.org/ntsb-events/332/sequence.md) - [Taxi-to runway: Fire/smoke (non-impact)](https://openairdocs.org/ntsb-events/150); cases with it: [Cirrus Design SR22T, 2 cases](https://openairdocs.org/ntsb-events/150/sequence.md?model=2130004), [All aircraft, 504 cases](https://openairdocs.org/ntsb-events/150/sequence.md) ## Analysis The airplane experienced an electrical fire while taxiing to the departure runway. A postaccident examination revealed that a grounded shield wire was improperly attached to the alternator's auxiliary power terminal instead of the alternator's case-ground connection during recent maintenance. The mechanic who had recently removed the alternator stated that he did not identify the location of the wire harness leads during removal and that the manufacturer's documentation did not depict where the power shield wire should be attached on the alternator, so he decided to attach the shield wire to the auxiliary power terminal, which was not correct. The manufacturer's wiring manual did not depict the optional electrical system wiring configuration, which included the incorporation of the No. 1 alternator power shield wire. As a result of the accident, the airplane manufacturer updated the wiring manual to explicitly account for the shield wires and the unused auxiliary power terminal. Caution messages were added to the maintenance manuals warning mechanics that the airplane might be equipped with cable shielding and, if so, where to connect the shielding on the alternator. ## Factual narrative On March 23, 2012, at 1100 central daylight time, a Cirrus Design Corporation model SR22T airplane, N229TX, was substantially damaged during an electrical fire while taxiing for departure at Addison Airport (ADS), Addison, Texas. The commercial pilot and passenger were not injured. The airplane was registered to and operated by PlaneSmart! Aviation LLC under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Day visual meteorological conditions prevailed for the local area flight that was originating when the accident occurred. The pilot reported that after a short taxi the primary flight display (PFD) and the multifunction display (MFD) suddenly lost all displayed information. The circuit breakers for battery No. 1 and alternator No. 2 had tripped and could not be reset. The pilot advised the tower controller that he wanted to return to the ramp. The tower controller told the pilot that the control tower was currently changing the active runways and to expect to hold his position for about 5 minutes. The pilot noted that airplane then experienced a total loss of electrical power. He decided to turn the airplane towards the control tower in order to look for light-gun signals from the control tower; however, the engine lost power as he increased power. At this time the passenger noticed smoke emanating from the lower engine compartment. The pilot and passenger exited the airplane and called the control tower via mobile phone to report the fire. The airplane had undergone recent maintenance that required the removal of the No. 1 alternator to facilitate the removal of an adjacent engine cylinder. A postaccident examination, completed by a Federal Aviation Administration (FAA) Airworthiness Inspector, revealed that the grounded shield wire for main power-out cable had been mistakenly attached to the auxiliary power terminal on the No. 1 alternator instead of the alternator's case-ground connection. There was extensive fire and heat damage to the No. 1 alternator wire harness, and to the associated ground buss and main control unit connectors. Additionally, the stainless steel heat shield and composite firewall exhibited fire and heat damage which necessitated major repair of the affected areas. According the FAA inspector, the aviation mechanic who had removed the No. 1 alternator did not mark or identify the location of the wire harness leads during removal. The mechanic referenced the Aircraft Wiring Manual (AWM) and Aircraft Maintenance Manual (AMM) before reinstalling the alternator, but was unable to determine the proper placement of the wire harness leads using the available documentation. The mechanic consulted with a co-worker on the placement of the grounded shield connector (which was partially obscured by shrink-wrap and not readily identifiable as being a shield wire). The decision was made to install the grounded shield wire to the auxiliary power terminal. (The auxiliary power terminal provides 1/3 of thetotal output capacity of the 100 ampere alternator.) According to the airplane manufacturer, a historical review of electrical schematics, airplane build records, and supporting engineering documentation established that the No. 1 alternator power shield wire was incorporated in the SR22 and SR22T airplane fleets to address reported electromagnetic interference on those airplanes equipped with a 100 ampere No. 1 alternator, storm scope, and air-conditioning. A review of the AWM confirmed that the auxiliary power terminal, and the optional power and field shield wires were not depicted in the electrical schematic and supporting documentation. As result of the accident, the airplane manufacturer updated the AWM alternator wiring depiction to explicitly account for the grounding shield wires and the unused auxiliary power terminal. Additionally, the AWM and AMM were both updated to include a caution message concerning the unused auxiliary power terminal that stated, "Do not install cable shielding wire(s) to the AUX power terminal." The updated AMM also included a caution message that stated, "Cable shielding could be installed to the power and/or field wire harness. If installed, attach cable shielding wire(s) to ground terminal on alternator." ## Aircraft - Registration: [N229TX](https://openairdocs.org/aircraft/N229TX), registered now, S/N 0076, built 2011 (OpenAirDocs) - Reported make and model: CIRRUS DESIGN CORPORATION SR22T - Registry model: [Cirrus Design SR22T](https://openairdocs.org/model/cirrus-design-sr22t) (registry code 2130004) (OpenAirDocs) - Registry engine: [Continental TSIO-550 series](https://openairdocs.org/engine/continental-tsio-550-series) (registry code 17043, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 0076 - Year built: 2011 - Airframe hours: 482 - Engines: Continental Motors TSIO-550-K 315 horsepower reciprocating - Damage: Substantial damage - Fire: On-Ground - Flight: Personal, Part 91 - Operator: PlaneSmart! Aviation, LLC - Registered owner: PlaneSmart! Aviation, LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 22, 2012 - Departed: ADS, Addison, TX - Destination: ADS, Addison, TX - Airport: ADS, Addison Airport, runway 15, 7,202 × 100 ft, asphalt - Equipment: Stall warning system, Electronic primary flight display, Electronic multifunction display, Airframe parachute ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 26; injuries: none; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 27, 2011; seat: left; restraint: 3-point; flight hours: 753 total, 23 in this make and model, 715 as pilot in command, 106 in the last 90 days, 44 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 45 °F - Altimeter: 30.05 inHg - Observed at: ADS ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20120323009079A](https://openairdocs.org/incident/20120323009079A), Mar 23, 2012: Cirrus Design Corp SR22T, Addison, TX, Substantial damage. 1.The mechanic disconnected the alternator #1 airframe side wiring harness from the #1 alternator to facilitate removal of the #3 and #5 engine cylinders. He… ## Docket (4 files) The files NTSB released with the investigation on May 6, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83278. 2.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 975 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411951&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - FAA Inspector Statement (Gavin Hill) (item 2, .PDF, 156 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411952&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement%20(Gavin%20Hill)-Redacted.PDF - Airplane Manufacturer's Report and Safety Improvements (item 3, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411953&FileExtension=.PDF&FileName=Airplane%20Manufacturer%27s%20Report%20and%20Safety%20Improvements-Redacted.PDF - NTSB Party Form (Cirrus Design Corporation) (item 4, .PDF, 242 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411954&FileExtension=.PDF&FileName=NTSB%20Party%20Form%20(Cirrus%20Design%20Corporation)-Redacted.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. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.