# NTSB ANC05LA097: Helio H-250, N333TB, Anchorage, AK, July 7, 2005 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 6, 2005, 18:00 local (Jul 7, 2005, 02:00 UTC) - Place: Anchorage, AK - Coordinates: 61.2, -149.833328 - Nearby events: https://openairdocs.org/map.md?lat=61.2000&lon=-149.8333&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report February 28, 2006 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration - NTSB case key (mKey): 61980 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC05LA097 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61980/pdf - Page: https://openairdocs.org/ntsb/ANC05LA097 ## Probable cause A fracture failure of the main landing gear leg during the landing roll, which resulted in the collapse of the main landing gear. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - landing gear,main gear strut - fractured (cause) - Gear collapsed, landing - roll - terrain condition - runway ## Analysis The first pilot, a certificated flight instructor, was providing flight instruction and recurrent training to the second pilot, a certificated private pilot. The first pilot said that after an uneventful touchdown on the dry and paved asphalt runway, a loud shuddering noise was heard as the second pilot applied the brakes. As the landing roll continued, the right main landing gear collapsed, and the right wing struck the runway. The airplane sustained structural damage to the right wing. A postaccident review of the fractured right main landing gear leg assembly in the fracture zone, disclosed brownish rust-colored deposits that covered about 1/4 of the circumference of the main landing gear tube. The remaining 3/4 circumference of the main landing gear tube had a 45-degree sheer lip, with the fracture surfaces consistent with an overload failure. ## Factual narrative On July 6, 2005, about 1800 Alaska daylight time, N333TB, a tailwheel-equipped Helio H-250 airplane, sustained substantial damage during the landing roll at the Merrill Field Airport, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) local area instructional flight under Title 14, CFR Part 91, when the accident occurred. The first pilot, a certificated flight instructor seated in the right seat, and the second pilot, a private pilot seated in the left seat, were not injured. The second pilot owned the accident airplane. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at the Merrill Field Airport, about 1700. During an on scene conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 6, the first pilot reported that he was providing flight instruction/recurrent training to the second pilot. The first pilot said that after an uneventful touchdown on the dry and paved asphalt of runway 24, a loud shuddering noise was heard as the second pilot applied the brakes. As they continued the landing roll, the right main landing gear collapsed, and the right wing struck the runway. The airplane sustained structural damage to the right wing. A postaccident inspection revealed that the right main landing gear leg assembly had fractured about 6 inches from the fuselage attach point. According to the airplane owner, the fractured main landing gear leg assembly, part number 250-040-451-1, had accumulated about 7,006 hours in service. The main landing gear leg assembly is constructed of 1/8-inch steel, which is molded and welding to form a 2-inch square steel tube. The main landing gear leg is covered by a contoured fairing assembly that conceals the area that fractured on the accident airplane. A visual inspection of the fractured right main landing gear leg assembly in the fracture zone area, revealed brownish rust-colored deposits that covered about 1/4 of the circumference of the main landing gear tube. The remaining 3/4 circumference of the main landing gear tube had a 45-degree sheer lip. ## Aircraft - Registration: [N333TB](https://openairdocs.org/aircraft/N333TB), registered now, S/N 2530 (OpenAirDocs) - Reported make and model: Helio H-250 - Registry model: [Helio H-250](https://openairdocs.org/model/helio-h-250) (registry code 4300302) (OpenAirDocs) - Category: Airplane - Serial number: 2530 - Airframe hours: 6088.5 - Engines: Lycoming O-540-A1B5 250 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Douglas R. Schrage - Airworthiness certificate: Standard, Normal - Last inspection: Annual, February 1, 2005, 17.8 hours before - Departed: MRI, Anchorage, AK - Destination: MRI, Anchorage, AK - Airport: MRI, Merrill Field, runway 24, 4,000 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 41; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review May 1, 2005; seat: right; flight hours: 3,070 total, 1,963 as pilot in command, 41 in the last 90 days, 17 in the last 30 days - Pilot; age 42; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review June 1, 2003; seat: left; flight hours: 1,245 total, 601 in this make and model, 1,186 as pilot in command, 14 in the last 90 days, 6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: 9,000 ft broken - Temperature: 72 °F, dew point 50 °F - Altimeter: 29.48 inHg - Observed at: MRI ## 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 20050707015029A](https://openairdocs.org/incident/20050707015029A), Jul 7, 2005: Helio H250, Anchorage, AK, Substantial damage. (-23) The aircraft landed normally on runway 24 and decelerated to taxi speed, approximately 1500 feet down the runway brakes were applied to exit the runway… ## Other investigations on N333TB (1) 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. - [NTSB ANC14CA087](https://openairdocs.org/ntsb/ANC14CA087), Sep 19, 2014: Helio H 250 (N333TB), Arctic Village, AK, substantial damage. Probable cause: The pilot's selection of an unsuitable landing/takeoff area, resulting in an inflight collision with terrain during takeoff. 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.