# NTSB CEN11CA152: Eurocopter Deutschland MBB-BK 117 C-2, N145SM, Albert Lea, MN, January 2, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: January 1, 2011, 18:14 local (Jan 2, 2011, 00:14 UTC) - Place: Albert Lea, MN - Coordinates: 43.652778, -93.371665 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.6528&lon=-93.3717&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report May 26, 2011 - Report: Approved by Office Director - NTSB office: Central Region - NTSB case key (mKey): 78154 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11CA152 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/78154/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=78154 - Page: https://openairdocs.org/ntsb/CEN11CA152 ## Probable cause The pilot's inadequate preflight inspection of the engine cowling latches prior the flight, which resulted in the cowling door opening in-flight and striking the main rotor blades. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Doors: service doors](https://openairdocs.org/ntsb-findings/01035240): Aircraft › Aircraft structures · Inadequate inspection (probable cause); cases with it: [All aircraft, 5 cases](https://openairdocs.org/ntsb-findings/01035240/cases.md) - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [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. - [Approach: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) ## Analysis The pilot said that he completed a preflight inspection at the beginning of his shift. He noted that earlier in the day, prior to the accident flight, he verified fuel control settings at the request of one of the mechanics. Both of these required that the engine cowling doors be opened. The pilot stated that prior to the accident flight, he visually checked the security of doors and cowlings, leaking fluids, tie downs, and the overall condition of the aircraft. He reported that after starting the number one engine, the flight medic commented that she heard an unusual sound. He subsequently asked her to check the security of the cowling door latches. When the flight medic returned, she informed him that the latches appeared to be secure. He stated that the flight proceeded without incident until about 1/2-mile from the destination helipad, he heard a loud bang and thump from the rear of the helicopter. Shortly thereafter the helicopter started to vibrate and he thought that the noise and vibration might be something from the rotor system. He elected to continue the approach to the destination helipad and subsequently landed without further incident. A postaccident examination revealed substantial damage to all four main rotor blades. The lower portion of the left engine cowling door was separated. No anomalies were observed with respect to the airframe side of the cowling door latches. The separated portion of the door was not recovered. ## Factual narrative The helicopter emergency medical services (HEMS) pilot stated that he had completed a pre-flight inspection at the beginning of his shift. He noted that earlier in the day, prior to the accident flight, he verified some fuel control settings at the request of one of the mechanics. Both of these required that the engine cowling doors be opened. The pilot stated that prior to the accident flight, he "visually checked for security of doors and cowlings, leaking fluids, tie downs, and overall condition of the aircraft." He reported that after starting the number one engine, the flight medic commented that she heard an "unusual rattle." The pilot subsequently asked her to check the security of the cowling door latches. When the flight medic returned, she informed him that the latches appeared to be secure. The pilot stated that the flight proceeded without incident until about one-half mile from the destination helipad, when he heard a "loud bang and thump from the rear of the aircraft." From that point in time, a "four per rev[olution] vibration had developed." He recalled thinking that due to the noise and vibration something might have separated from the rotor system. He elected to continue the approach to the destination helipad and subsequently landed without further incident. A post accident examination revealed substantial damage to all four main rotor blades. The lower portion of the left engine cowling door was separated. No anomalies were observed with respect to the airframe side of the cowling door latches. The separated portion of the door was not recovered. The helicopter was being repositioned in order to pick-up a patient, and only the pilot and medical crew were on-board at the time of the accident. ## Aircraft - Registration: N145SM (not matched to a registry record) - Reported make and model: EUROCOPTER DEUTSCHLAND GMBH MBB-BK 117 C-2 - Category: Helicopter - Serial number: 9298 - Airframe hours: 490 - Engines: Turbomeca Arriel 1E2 758 horsepower turbo shaft; Turbomeca Arriel 1E2 758 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Operator: Omniflight Helicopters, Inc. - Registered owner: Wells Fargo Bank Northwest Na Trustee - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, December 28, 2010 - Departed: 99MN, Rochester, MN - Destination: 30MN, Albert Lea, MN - Flight plan: Company VFR - Airport: 30MN, Albert Lea Medical Center ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; commercial; airplane ratings: multi-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review September 8, 2010; seat: right; flight hours: 5,520 total, 130 in this make and model, 5,520 as pilot in command, 54 in the last 90 days, 6 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night - Wind: 270° at 19 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 5 °F, dew point -0 °F - Altimeter: 29.09 inHg - Observed at: RST, 39 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 20110101004179A](https://openairdocs.org/incident/20110101004179A), Jan 1, 2011: Eurocopter Deutschland Gmbh MBB-BK 117 C-2, Albert Lea, MN, Substantial damage. On 1/1/11 approximately 1700 local time omniflight dispatch contacted [privacy data omitted] with a request to reposition from rochester MN to Albert Lea… ## Docket (4 files) The files NTSB released with the investigation on February 16, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=78154. 2.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 847 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342942&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Statement -- Pilot (item 2, .PDF, 521 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342943&FileExtension=.PDF&FileName=Statement%20--%20Pilot-Redacted.PDF - Statement -- Flight Nurse (item 3, .PDF, 613 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342912&FileExtension=.PDF&FileName=Statement%20--%20Flight%20Nurse-Redacted.PDF - Statement -- Paramedic (item 4, .PDF, 276 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342914&FileExtension=.PDF&FileName=Statement%20--%20Paramedic-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.