# NTSB SEA96IA074: Dornier DO 328-100, N334PH, Eugene, OR, March 31, 1996 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: March 31, 1996, 06:30 local (14:30 UTC) - Place: Eugene, OR - Coordinates: 44.039054, -123.219619 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.0391&lon=-123.2196&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 27 uninjured - Status: Completed, report February 28, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 42293 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA96IA074 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42293/pdf - Page: https://openairdocs.org/ntsb/SEA96IA074 ## Probable cause delamination of the wing de-icing boot, due to the boot reaching its life limit. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, climb - to cruise - anti-ice/deice system,wing - life expired (cause) - anti-ice/deice system,wing - delamination (cause) ## Analysis The flight crew reported that as the airplane was climbing between 14,000 feet and 16,000 feet in light icing conditions, they felt a moderate shudder. The autopilot disconnected, and the airplane immediately rolled 15 degrees to the left. An emergency was declared, and the flight was diverted with no further incident. After landing, examination revealed that a section of the left wing de-icing boot had delaminated. When pressure was applied to the system, a bubble was created. When pressure was off, the delaminated plies were stretched beyond their elastic limits and would not return to the normal shape, thus creating wrinkles. Examination of the plies revealed that there was no evidence of contamination. The separation occurred between the adhesion coat and the knit fabric. The manufacturer of the boot reported that this mode of failure was consistent with an elastromeric construction that had reached the end of its useful life. The outer delaminated plies were found to be unusually durable, which resulted in a large bubble instead of the normally expected 'burst' of the outer plies. ## Factual narrative On March 31, 1996, at 0630 Pacific standard time, a Dornier Luftfahrt GMBH DO 328-100, N334PH, flight number 2620, registered to First Security Bank of Utah, operated by Horizon Air as a 14 CFR Part 121 passenger flight, diverted to Portland, Oregon, after the flight crew felt a shudder and an immediate roll to the left. The flight crew declared an emergency and landed at Portland without further incident. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The airplane received minor damage and there were no injuries to the 24 passengers, one flight attendant, and the two airline transport pilots. The flight originated from Eugene, Oregon, about 30 minutes before the incident. The flight crew reported that as the airplane was climbing between 14,000 feet and 16,000 feet, at 200 KIAS in light icing conditions, they felt a moderate shudder. The auto pilot disconnected and the airplane immediately rolled 15 degrees to the left. An emergency was declared and the flight was diverted to Portland. After landing, it was found that a portion of the left wing leading edge de-icing boot was loose. When air pressure was applied to the boot, a 12 inch diameter "bubble" formed six inches in from the outboard section of the middle boot. When air pressure was removed, that portion of the boot remained loose. The boot was removed from the wing and transported to Daimler-Benz Aerospace, Germany. The boot was installed on a test airplane and wind tunnel tested. The test revealed that the airplane was controllable even with the delamination in front of the aileron. The boot was removed and transported to BFGoodrich Ice Protection Systems, Uniontown, Ohio to determine the reason for the delamination. Preliminary inspection determined that the delaminated plies had stretched beyond their elastic limits and would not return to the normal shape upon deflation. The result was permanent wrinkles in the affected area. Samples of the affected area were taken and examined under optical microscopy and scanning electron microscopy. The result of the examination revealed no evidence of contamination. Peel adhesion samples were then constructed and found that the separation occurred between the adhesion coat and the knit fabric. BFGoodrich reports that this mode of failure is consistent with an elastromeric construction de-icer that has reached the end of its useful life. The outer delaminated plies were found to be unusually durable which resulted in a large bubble instead of the normally expected "burst" of the outer plies. ## Aircraft - Registration: [N334PH](https://openairdocs.org/deregistered/N334PH-2014-10-06), registration cancelled 2014-10-06, S/N 3012, built 1994 (OpenAirDocs) - Reported make and model: Dornier DO 328-100 - Registry model: [Dornier Luftfahrt DO 328-100](https://openairdocs.org/model/dornier-luftfahrt-do-328-100) (registry code 2996000) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PW119C](https://openairdocs.org/engine/pratt-whitney-canada-pw119c) (registry code 52163, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 3012 - Airframe hours: 4331 - Engines: P&W 119B 2180 horsepower turbo prop - Damage: Minor damage - Flight: Part 121 - Operator: Horizon Air - Registered owner: First Security Bank Of Utah - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, March 28, 1996 - Departed: EUG, OR - Destination: SEA, SEATTLE, WA - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; flight instructor, airline transport, commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 5,266 total, 1,897 as pilot in command, 178 in the last 90 days, 59 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19960331044229I](https://openairdocs.org/incident/19960331044229I), Mar 31, 1996: Dorner DO328100, Eugene, OR, Minor damage. (-5)The flight crew reported that as the airplane was climbing between 14,000 feet and 16,000 feet in light icing conditions, they felt a moderate shudder. The… 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.