# NTSB ATL96LA073: Canadair CL-600S, N999TF, Raleigh, NC, April 1, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 1, 1996, 10:04 local (15:04 UTC) - Place: Raleigh, NC - Location: 35.8667° N, 78.7992° W: Placed by OpenAirDocs from NTSB’s distance and direction from RALEIGH-DURHAM INTL (RDU), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=35.8667&lon=-78.7992&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 9 uninjured - Status: Completed, report August 29, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 3717 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL96LA073 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3717/pdf - Page: https://openairdocs.org/ntsb/ATL96LA073 ## Probable cause the flight crew's inadequate emergency procedure in that they did not manually extend the landing gear, as specified in the airplane flight manual. A factor relating to the accident was: the intermittent operation of the extend solenoid in the nose gear selector valve. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - landing gear,normal retraction/extension assembly - malfunction (contributing factor) - landing gear,nose gear - not engaged - gear down and locked - not attained, flightcrew (cause) - emergency procedure - not followed, flightcrew (cause) - Nose gear collapsed, landing - flare/touchdown ## Analysis During an instrument landing system (ILS) approach the airline transport pilot noticed a discrepancy in the landing gear indicators. He raised the landing gear and lowered it again. The main landing gear indicator lights were illuminated, indicating that the main gear was extended and locked, but the nose gear light was extinguished. The light in the gear handle was off, indicating that the system was functioning properly. The pilot did not use the emergency landing gear extension system. The aircraft was landed, and the nose gear collapsed. Subsequent examination revealed an intermittently operating extend solenoid in the nose gear selector valve. ## Factual narrative On April 1, 1996, about 1004 eastern standard time, Canadair CL-600-1A11, N999TF, nose landing gear collapsed on landing at the Raleigh-Durham Airport, Raleigh, North Carolina. The aircraft was being operated by Pal-Waukee Aviation under the provisions of 14 CFR Part 135 and instrument flight rules. Instrument meteorological conditions existed at the time of the accident, and an instrument flight rules flight plan was in effect. The airline transport pilot, his co-pilot, the cabin attendant, and the six passengers were not injured; the aircraft was substantially damaged. The flight departed Milwaukee, Wisconsin at 0830 the same day. The pilot stated that when the landing gear was extended, the landing gear position indicating system presented conflicting information regarding the position of the nose landing gear. The landing gear was then raised, and the indicator lights were all extinguished. The gear was again extended. The main gear indicator lights were illuminated, indicating that the main gear was down, but the nose gear light was extinguished. The light in the gear handle was off, indicating that the system was functioning properly. The pilot did not use the emergency landing gear extension system. The aircraft was landed and the nose gear collapsed. The pilot stated that the clouds and visibility precluded any observation of the landing gear by airport tower personnel. Post accident examination of the nose gear selector valve revealed an intermittently inoperative extend solenoid valve. According to the failure analysis report, the solenoid valve most likely experienced moisture entry. The manufacturer reported that the selector valve was repaired with an upgraded solenoid to preclude recurrence of the failure. ## Aircraft - Registration: N999TF (not matched to a registry record) - Reported make and model: Canadair CL-600S - Category: Airplane - Serial number: 1042 - Airframe hours: 3395 - Engines: ALLIED SIGNAL ALF502L2C 7500 horsepower turbo fan - Damage: Substantial damage - Flight: Part 135 - Operator: Pal-Waukee Aviation, doing business as Priester Aviation - Registered owner: U.S. Bancorp Leasing & Financ. - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, January 29, 1996, 46 hours before - Departed: MKE, MILWAUKEE, WI - Destination: RDU - Flight plan: IFR - Airport: RDU, Raleigh-Durham, runway 23R, 10,000 × 150 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 6,500 total, 1,014 in this make and model, 3,750 as pilot in command, 155 in the last 90 days, 53 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 340° at 3 knots - Visibility: 3 statute miles - Lowest ceiling: 300 ft overcast - Temperature: 52 °F, dew point 54 °F - Altimeter: 29.00 inHg - Observed at: RDU, 1 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 19960401005709A](https://openairdocs.org/incident/19960401005709A), Apr 1, 1996: Cndair CL6001A11, Raleigh-Durham, NC, Substantial damage. Nose gear collapsed landing. Had indication nose gear not locked. Did not use manual system. Faulty solenoid valve. 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.