# NTSB WPR13LA290: Mcdonnell Douglas Helicopter 369E, N34CT, Casa Grande, AZ, June 25, 2013 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 25, 2013, 06:50 local (13:50 UTC) - Place: Casa Grande, AZ - Coordinates: 32.838054, -111.724723 - Nearby events: https://openairdocs.org/map.md?lat=32.8381&lon=-111.7247&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 3 minor - Status: Completed, report February 10, 2014 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Boeing, Pinal County Sheriff, MDHI, FAA FSDO, Rolls Royce - NTSB case key (mKey): 87292 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR13LA290 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87292/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87292 - Page: https://openairdocs.org/ntsb/WPR13LA290 ## Probable cause The total loss of engine power due to the ingestion of a foreign object and maintenance personnel's failure to remove shop rags before completing the installation of the air inlet barrier system. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (turbine/turboprop): air inlet section (core eng)](https://openairdocs.org/ntsb-findings/01057220): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [All aircraft, 4 cases](https://openairdocs.org/ntsb-findings/01057220/cases.md) - [Maintenance: modification/alteration](https://openairdocs.org/ntsb-findings/02062030): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [All aircraft, 69 cases](https://openairdocs.org/ntsb-findings/02062030/cases.md) - [Performance/control parameters: engine out control](https://openairdocs.org/ntsb-findings/01062025): Aircraft › Aircraft oper/perf/capability · Not attained/maintained; cases with it: [All aircraft, 35 cases](https://openairdocs.org/ntsb-findings/01062025/cases.md) - [Performance/control parameters: landing flare](https://openairdocs.org/ntsb-findings/01062041): Aircraft › Aircraft oper/perf/capability · Incorrect use/operation; cases with it: [All aircraft, 1,285 cases](https://openairdocs.org/ntsb-findings/01062041/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot; cases with it: [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis Before the accident flight, maintenance personnel exchanged the helicopter's air inlet barrier filter system, during which the engine was removed from the helicopter. A preflight inspection was completed before departure of the postmaintenance check flight, and no discrepancies were noted. The engine start and pretakeoff checks were normal, and, after departure, the flight appeared to progress normally. About 1 to 2 minutes after completing an in-flight power check, the pilot heard a "distinct loud pop." Subsequently, the engine lost total power, and the pilot entered an autorotation. The helicopter landed hard, its right skid collapsed, and it rolled on its right side. A postaccident examination of the helicopter's engine air inlet found that cloth material had been ingested into the engine air intake. During further examinations, more cloth material was found in the engine in a sufficient quantity and location to block the airflow through the engine and cause it to flame out. The cloth material found in the engine was consistent with maintenance rags found in a box at the operator's hangar facility. It is likely that, during the maintenance of the helicopter's engine, maintenance personnel covered vulnerable areas of the engine with shop rags to prevent contamination, and, during the reinstallation of the engine, they did not remove all of the shop rags. The engine then ingested the rags during the postmaintenance test flight. Due to the installation of the engine air inlet barrier system, the shop rags would not have been visible during the preflight inspection nor could they have made it into the engine from the outside of the helicopter with the system in place. ## Factual narrative On June 25, 2013, about 0650 mountain standard time, a McDonnell Douglas 369E helicopter, N34CT, sustained substantial damage during an off-airport hard landing, about 6 miles south-southeast of Casa Grande, Arizona. The helicopter was being operated by the Pinal County Sheriff's Office as a day, visual flight rules, post maintenance test flight, under the provisions of Title 14, CFR Part 91. The three occupants of the helicopter sustained minor injuries. Visual meteorological conditions prevailed, and company flight following procedures were in effect. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot said they were flying about 700 feet above the ground performing a post-maintenance test flight, when he heard an audible bang. The helicopter engine lost all engine power, and he did an autorotation. The helicopter landed hard, the right skid collapsed, and the helicopter came to rest on its right side. The tailboom and fuselage sustained substantial damage. The helicopter was being test flown with maintenance personnel on-board, following the modification of the air intake. In a written statement to the NTSB dated July 1, the pilot reported that he arrived at the Sheriff's hangar facility, and met with their aircraft mechanic, and another deputy/tactical flight officer. Their mission was to do a post maintenance test flight on the accident helicopter. This was the first flight since the installation of a Donaldson Air Filtration System and a new horizontal stabilizer. A pre-flight inspection was completed, and the pre-engine start checks were performed via a checklist. The engine start was normal. Pre-takeoff checks were performed per the checklist. No discrepancies were observed during the run-up. In a hover, all the flight controls and the engine indications were normal. The pilot hover taxied the helicopter to a ramp area, and performed a few hover maneuvers to ensure control inputs were normal. Once the maneuvers were complete, they departed the airport to the south-southeast. During the departure flight, the engine and flight instruments operated normally. A power check was completed; the pilot reduced the torque, and climbed to 2,100 feet(600-700 feet above ground level) where he leveled off. He continued cruise flight at about 110 knots. About 1-2 minutes after the power check, the pilot heard a distinct loud pop, the nose yawed to the left, and the helicopter begin to descend. The pilot, noting the loss of engine power, entered an autorotation. Approaching the ground, the pilot flared hard, leveled the helicopter, and pulled in collective. The helicopter landed hard, the right skid collapsed, and the helicopter rolled on its side. The helicopter was examined at the accident site by an Federal Aviation Administration (FAA) aviation safety inspector (ASI). The helicopter was recovered to the Sheriff's hangar. At the direction of the NTSB IIC, the helicopter wasexamined under the supervision of the FAA ASI, by representatives/investigators from the airframe and engine manufacturers, in the presence of the operator's representatives. During the examination, the investigators removed the air intake assembly, and found cloth material had been ingested into the engine intake. The engine was removed and shipped to the engine manufacturer's authorized maintenance facility for further examination. No other anomalies were found during the examination of the airframe. An examination of the helicopter's maintenance logbooks revealed that the helicopter was being returned to service after an exchange of the air inlet barrier filter system. During the exchange the engine had been removed from the helicopter. According to a mechanic, the engine was re-installed and inspected, prior to the air inlet barrier filter system installation. At the engine manufacturer's authorized maintenance facility, the engine was disassembled and examined under the supervision of an FAA ASI, in the presence of the operator's representative. During the examination, more cloth material was found in the engine, in a sufficient quantity and location to cause engine flame out. The cloth material found in the engine was consistent with a box of maintenance rags found at the operator's hangar facility. ## Aircraft - Registration: N34CT (not matched to a registry record) - Reported make and model: MCDONNELL DOUGLAS HELICOPTER 369E - Category: Helicopter - Serial number: 0392E - Airframe hours: 4785 - Engines: Rolls Royce M250-C20R2 450 horsepower turbo shaft - Damage: Substantial damage - Flight: Flight test, Part 91 - Operator: Pinal County Sheriff's Office - Registered owner: Pinal County Sheriff's Office - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 8, 2013 - Departed: KCGZ, Casa Grande, AZ - Destination: KCGZ, Casa Grande, AZ - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: minor; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review August 2, 2012; seat: left; restraint: 4-point; flight hours: 1,208 total, 498 in this make and model, 1,074 as pilot in command, 88 in the last 90 days, 29 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F - Altimeter: 29.93 inHg - Observed at: KCGZ, 170 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 20130625012029A](https://openairdocs.org/incident/20130625012029A), Jun 25, 2013: Mcdonnell Douglas Helicopter 369E, Casa Grande, AZ, Substantial damage. On 6-25-13 at approximately 0645 MST N34CT, MD-369 helicopter departed Casa Grande Municipal (cgz) airport for a maintenance flight. This flight was the first… ## Docket (9 files) The files NTSB released with the investigation on November 20, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87292. 7.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402604&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statement (item 2, .PDF, 132 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402999&FileExtension=.PDF&FileName=Witness%20Statement-Master.PDF - Rolls-Royce Engine Investigaiton Report (43 Embedded Images) (item 3, .PDF, 43 photos, 4.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403886&FileExtension=.PDF&FileName=Rolls-Royce%20Engine%20Investigaiton%20Report%20(43%20Embedded%20Images)-Redacted.PDF - Statement of Party Representatives to NTSB Investigation - The Boeing Company (item 4, .PDF, 152 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402609&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation%20-%20The%20Boeing%20Company-Redacted.PDF - Statement of Party Representatives to NTSB Investigation - Pinal County Sheriff's Office (item 5, .PDF, 246 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402611&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation%20-%20Pinal%20County%20Sheriff%27s%20Office-Redacted.PDF - Statement of Party Representatives to NTSB Investigation - Pinal County Sheriff's Office (item 6, .PDF, 244 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402615&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation%20-%20Pinal%20County%20Sheriff%27s%20Office-Redacted.PDF - Statement of Party Representatives to NTSB Investigation - MD Helicopter Inc. (item 7, .PDF, 318 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402613&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation%20-%20MD%20Helicopter%20Inc.-Redacted.PDF - Statement of Party Representatives to NTSB Investigation - Rolls-Royce (item 8, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40402617&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation%20-%20Rolls-Royce-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 9, .PDF, 61 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403064&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-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.