# NTSB CEN12CA474: Eurocopter Deutschland MBB-BK 117 C-2, N455MH, Houston, TX, July 24, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: July 24, 2012, 06:08 local (11:08 UTC) - Place: Houston, TX - Coordinates: 29.707777, -95.390556 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.7078&lon=-95.3906&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report October 9, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Houston FSDO - NTSB case key (mKey): 84431 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12CA474 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/84431/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=84431 - Page: https://openairdocs.org/ntsb/CEN12CA474 ## Probable cause The pilot’s inadequate preflight inspection, which failed to detect the unsecured cowling latches and resulted in the in-flight opening of an engine cowling. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant: engine cowling system](https://openairdocs.org/ntsb-findings/01057110): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [Eurocopter Deutschland MBB-BK 117 C-2, 1 case](https://openairdocs.org/ntsb-findings/01057110/cases.md?model=5626002), [All aircraft, 11 cases](https://openairdocs.org/ntsb-findings/01057110/cases.md) - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Eurocopter Deutschland MBB-BK 117 C-2, 1 case](https://openairdocs.org/ntsb-findings/02061510/cases.md?model=5626002), [All aircraft, 551 cases](https://openairdocs.org/ntsb-findings/02061510/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 inspection event](https://openairdocs.org/ntsb-events/050); cases with it: [Eurocopter Deutschland MBB-BK 117 C-2, 1 case](https://openairdocs.org/ntsb-events/050/sequence.md?model=5626002), [All aircraft, 229 cases](https://openairdocs.org/ntsb-events/050/sequence.md) - [Landing: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Eurocopter Deutschland MBB-BK 117 C-2, 3 cases](https://openairdocs.org/ntsb-events/900/sequence.md?model=5626002), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Landing: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Eurocopter Deutschland MBB-BK 117 C-2, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=5626002), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The emergency medical services helicopter was about 800 feet above ground level and landing at a rooftop hospital helipad in a congested metropolitan area when the left side engine cowling opened. The cowling partially separated and impacted the bottom of all four main rotor blades, resulting in substantial damage to the rotor blades. The pilot described the event as a brief shudder, like flying through the rotor wash of another helicopter. The pilot was unaware that any damage had occurred and landed uneventfully. A third medical crewmember boarded through the right rear door for a local flight to a suburban hospital. During engine shutdown at their destination, another medical crewmember exited the helicopter on the left side and was the first to notice the damage. The pilot stated that he failed to complete a thorough preflight inspection before the accident flight, because the crew was assigned a medical mission just after their shift started. The previous pilot, who flew the helicopter the evening before the accident, stated that he had opened the left side engine cowling to check the oil level and became distracted. He also stated that he could not remember if he had secured the cowling latches. ## Factual narrative The emergency medical service helicopter was about 800 feet above ground level and landing at a rooftop hospital helipad in a congested metropolitan area when the left side engine cowling opened. The cowling partially separated and caused substantial damage when it impacted the bottom of all four main rotor blades. The pilot described the event as a brief shudder like flying through the rotor wash of another helicopter. The pilot was then unaware that any damage had occurred and landed uneventfully. A third medical crewmember then boarded through the right rear door for a local flight to a suburban hospital. During engine shutdown at their destination, another medical crewmember exited the helicopter on the left side and was the first to notice the damage. The pilot stated he failed to complete a thorough preflight inspection because the crew was assigned a medical mission just after their shift started. The previous pilot who flew the helicopter the evening before the accident stated that he had opened the left side engine cowling to check the oil level and became distracted. He also stated he could not remember if he had secured the cowling latches. ## Aircraft - Registration: [N455MH](https://openairdocs.org/aircraft/N455MH), registered now, S/N 9161, built 2008 (OpenAirDocs) - Reported make and model: EUROCOPTER DEUTSCHLAND GMBH MBB-BK 117 C-2 - Registry model: [Eurocopter Deutschland MBB-BK 117 C-2](https://openairdocs.org/model/eurocopter-deutschland-mbb-bk-117-c-2) (registry code 5626002) (OpenAirDocs) - Registry engine: [Turbomeca ARRIEL-1E2](https://openairdocs.org/engine/turbomeca-arriel-1e2) (registry code 60035, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 9161 - Airframe hours: 2305 - Engines: TURBOMECA ARRIEL 1E2 708 horsepower turbo shaft; TURBOMECA ARRIEL 1E2 708 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Operator: Memorial Hermann Hospital System, doing business as Life Flight - Registered owner: Memorial Hermann Hospital System - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, July 2, 2012, 9 hours before - Departed: NONE, Katy, TX - Destination: 38TE, Houston, TX - Flight plan: Company VFR - Airport: 38TE, John S Dunn Helistop ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; airline transport; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; last flight review November 15, 2011; seat: right; flight hours: 3,784 total, 597 in this make and model, 3,784 as pilot in command, 61 in the last 90 days, 21 in the last 30 days ## Weather - Conditions: Visual (VMC), Night - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 75 °F - Altimeter: 30.06 inHg - Observed at: KHOU, 7 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 20120724015589A](https://openairdocs.org/incident/20120724015589A), Jul 24, 2012: Eurocopter Deutschland Gmbh MBB-BK 117 C-2, Houston, TX, Substantial damage. Medical flight (life flight 5) from 70TS to memorial hermann hospital s.e. with stop at 38TE to pick up a nurse. Upon approach to 38TE the pilot and crew heard… ## Docket (7 files) The files NTSB released with the investigation on August 10, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=84431. 2.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 566 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374976&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Crewmember Statements (item 2, .PDF, 272 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374684&FileExtension=.PDF&FileName=Crewmember%20Statements-Redacted.PDF - Statement From Previous Pilot (item 3, .PDF, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374685&FileExtension=.PDF&FileName=Statement%20From%20Previous%20Pilot-Master.PDF - Weather Summary (item 4, .PDF, 83 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374977&FileExtension=.PDF&FileName=Weather%20Summary-Master.PDF - Photo 1 - Preaccident Photo Showing Left Side of Helicopter (item 5, .PDF, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374688&FileExtension=.PDF&FileName=Photo%201%20-%20Preaccident%20Photo%20Showing%20Left%20Side%20of%20Helicopter-Master.PDF - Photo 2 - Partially Separated Left Side Engine Cowling (item 6, .PDF, 769 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374691&FileExtension=.PDF&FileName=Photo%202%20%20-%20Partially%20Separated%20Left%20Side%20Engine%20Cowling-Master.PDF - Photo 3 - Damage to Main Rotor Blade (item 7, .PDF, 767 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374693&FileExtension=.PDF&FileName=Photo%203%20-%20Damage%20to%20Main%20Rotor%20Blade-Master.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.