# NTSB WPR11LA122: McDonnell Douglas Helicopters 369E (MD500E), N416WC, Elverta, CA, February 4, 2011 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: February 4, 2011, 14:22 local (22:22 UTC) - Place: Elverta, CA - Coordinates: 38.718334, -121.478332 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.7183&lon=-121.4783&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-hover: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report March 28, 2012 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Wilson Construction, Rolls-Royce, FAA FSDO, Boeing - NTSB case key (mKey): 78282 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11LA122 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78282/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78282 - Page: https://openairdocs.org/ntsb/WPR11LA122 ## Probable cause The pilot did not maintain rotor blade clearance from an installation rope while maneuvering to install power lines. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) - [Object/animal/substance: wire](https://openairdocs.org/ntsb-findings/03022032): Environmental issues › Physical environment · Response/compensation (probable cause); cases with it: [All aircraft, 588 cases](https://openairdocs.org/ntsb-findings/03022032/cases.md) - [Attention/monitoring: monitoring environment](https://openairdocs.org/ntsb-findings/02021545): Personnel issues › Psychological · Pilot (probable cause); cases with it: [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/02021545/cases.md) - [Object/animal/substance: wire](https://openairdocs.org/ntsb-findings/03022032): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [All aircraft, 588 cases](https://openairdocs.org/ntsb-findings/03022032/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-hover: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) (defining event); cases with it: [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md) ## Analysis A lineman was on the skid of the helicopter installing high-power electrical lines on a power line structure. The pilot positioned the helicopter about 30 to 50 feet from the structure. The main rotor blades made contact with an installation rope, which then wrapped around the mast as the blades pulled it in. The pilot lost control of the helicopter, and it began an uncontrolled descent to the ground. A postaccident examination of the airframe and engine revealed no mechanical anomalies that would have precluded normal operation. It is likely that the pilot misjudged the distance between the rotor blades and the installation rope. ## Factual narrative HISTORY OF FLIGHT On February 4, 2011, about 1422 Pacific standard time, a McDonnell Douglas Helicopters 369E (MD500E), N416WC, became entangled with a sock line rope used to string power lines near Elverta, California. Wilson Construction Company was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 133. The commercial pilot and one passenger sustained minor injuries; the helicopter sustained substantial damage to the airframe and main rotor blades. Visual meteorological conditions prevailed, and no flight plan had been filed. The operator reported that the helicopter was working on a project to construct 30 miles of high power electrical lines, which are oriented north-south. It is not possible to pull the conductor wire through bundled travelers unless the sock line is actually in contact with the roller. Construction crews install a hold down, which is a temporary block that they secure to a ground anchor. They adjust the anchor rope to force the sock line to rest in the bundle block traveler when in tension. The operator noted that it is standard industry practice to use a helicopter to install a hold down. A lineman was on the skid of the helicopter, which was in position to install a hold down at a power line structure. The pilot positioned the helicopter about 30-50 feet south of the structure; his flagman was facing the west. The pilot believed that he was properly positioned near the sock line so that they could perform the task safely. The lineman on the skid placed the larger of the two hold down ropes over the sock line, and allowed it to fall onto the west side. The lineman allowed the hold down block to hang by the large rope just below and on the east side of the sock line. The large rope tangled as it fell to the ground. The lineman on the ground grabbed the end of the rope, and tried to clear the tangle. The lineman on the skid had one hand on the hold down, and was preparing to release the second, smaller rope downward on the western side of the sock line with the other hand. The main rotor blades made contact with the sock line rope, which wrapped around the mast as the blades pulled it in. The pilot lost control of the helicopter, and it began an uncontrolled descent to the ground. The helicopter came to rest upright about 10 feet south of the power line structure. The lineman on the skid was lying on the ground, but still attached to the helicopter by her fall restraint and positioning belt. The pilot extricated himself from the helicopter. TESTS AND RESEARCH Investigators from the FAA, Boeing, and Rolls-Royce Allison (RR) examined the wreckage at the operator’s facilities at McLellan Airfield, Sacramento, California, on February 9, 2011. The investigators examined the airframe and engine, with no mechanical anomalies identified that would have precluded normal operation. ## Aircraft - Registration: N416WC (not matched to a registry record) - Reported make and model: McDonnell Douglas Helicopters 369E (MD500E) - Category: Helicopter - Serial number: 0268E - Airframe hours: 6256 - Engines: Rolls-Royce Allison 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 133 - Operator: Wilson Construction Company - Registered owner: Wilson Construction Company - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, January 26, 2011 - Departed: Elverta, CA - Destination: Elverta, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: minor; commercial; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review February 11, 2010; seat: left; flight hours: 22,500 total, 17,600 in this make and model, 22,500 as pilot in command, 75 in the last 90 days, 20 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dawn - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 59 °F, dew point 43 °F - Altimeter: 30.30 inHg - Observed at: KSMF, 6 nm away ## 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 20110204002599A](https://openairdocs.org/incident/20110204002599A), Feb 4, 2011: Mcdonnell D 369E, Elverta, CA, Substantial damage. While assisting in hanging tensioning pullies on pull rope used to string cables between large electrical towers, helicopter came in contact with pull rope… ## Docket (4 files) The files NTSB released with the investigation on February 13, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78282. 1.4 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 706 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40363350&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Boeing Field Notes (item 2, .PDF, 48 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40361877&FileExtension=.PDF&FileName=Boeing%20Field%20Notes-Master.PDF - Rolls Royce Exam Notes (item 3, .PDF, 89 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40361878&FileExtension=.PDF&FileName=Rolls%20Royce%20Exam%20Notes-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 4, .PDF, 510 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40362608&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-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.