# NTSB CEN17LA057: Stinson 108-3, N812C, Ionia, MI, December 16, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 16, 2016, 10:45 local (15:45 UTC) - Place: Ionia, MI - Coordinates: 42.938056, -85.060554 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.9381&lon=-85.0606&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 6, 2017 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, Grand Rapids FSDO - NTSB case key (mKey): 94514 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA057 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94514/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94514 - Page: https://openairdocs.org/ntsb/CEN17LA057 ## Probable cause A failure of the aft support cable on the left main landing ski due to an inadequately formed nicopress sleeve, which allowed the ski to rotate into a vertical position shortly after liftoff, and its unavoidable separation during the subsequent landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance: fabrication](https://openairdocs.org/ntsb-findings/02062025): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-findings/02062025/cases.md?model=9230408), [All aircraft, 30 cases](https://openairdocs.org/ntsb-findings/02062025/cases.md) - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md?model=9230408), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md) - [Misc hardware: fasteners](https://openairdocs.org/ntsb-findings/01071430): Aircraft › Fluids/misc hardware · Incorrect service/maintenance (probable cause); cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-findings/01071430/cases.md?model=9230408), [All aircraft, 58 cases](https://openairdocs.org/ntsb-findings/01071430/cases.md) - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md?model=9230408), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Stinson 108-3, 11 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=9230408), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/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 maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=9230408), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Takeoff: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=9230408), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=9230408), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Landing: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Stinson 108-3, 12 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=9230408), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Stinson 108-3, 13 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=9230408), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The private pilot reported that, shortly after takeoff from a snow-covered runway, he heard a "thump" and saw that the left main landing ski tip had rotated up, past vertical, and was in contact with the left wing strut. He was unable to reposition the left ski into a normal position. Upon landing, the ski separated from the axle, the left gear leg dug into the snow, and the airplane rapidly decelerated before it nosed over. As designed, the main landing skis are supported by two 5/32-in braided steel cables and bungee/shock cords. Both ends of the steel cables terminate with a thimble-eye and a compressed/swaged nicopress sleeve. On the accident airplane, the forward and aft support cables had pulled through their respective nicopress sleeves where the cables attached to the left ski's tip and tail. The nicopress sleeves for the left ski tip and tail attachments were not located during the investigation. However, a postaccident examination of the remaining nicopress sleeves established that they were likely improperly formed with a 3/16-in swage tool instead of a properly-sized 5/32-in tool. As a result, the steel support cables were able to pull through the inadequately-formed nicopress sleeves during the accident flight. It is likely that the aft support cable pulled through its nicopress sleeve during takeoff, which allowed the ski to rotate into a vertical position. The forward support cable likely pulled through its nicopress sleeve when the left ski separated from the axle during the subsequent landing. The pilot reported that the airplane was typically equipped with snow skis during the winter. He purchased the main landing skis in used condition, with an undocumented service history, from an individual about 8 years before the accident. The forward and aft support cables were already fabricated and installed on the skis when they were purchased. Additionally, the pilot reported that the support cables had not been repaired or replaced since he owned the skis. The pilot, who was also an aviation mechanic, installed the main landing skis for the winter snow season 2 days before the accident. The accident occurred during the first flight since the skis were installed for the season. ## Factual narrative On December 16, 2016, about 1045 eastern standard time, a Stinson model 108-3 single-engine airplane, N812C, equipped with snow skis, was substantially damaged while landing at Ionia County Airport (Y70), Ionia, Michigan. The private pilot, the sole occupant, was not injured. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions prevailed for the flight that departed Lowell City Airport (24C), Lowell, Michigan, about 1030.The pilot reported that shortly after takeoff from a snow covered runway he heard a thump and saw that the left main landing ski tip had rotated up, past vertical, and was in contact with the left wing strut. He decided to land at nearby Y70 because he anticipated requiring assistance upon landing and the departure airport was unmanned. Additionally, Y70 had a snow covered turf runway, south of the paved runway 9/27, that was typically used for glider operations. The pilot reported that he was unable to reposition the left ski into a normal position and upon landing the ski separated from the axle, the left gear leg dug into the snow, and the airplane rapidly decelerated before it nosed over. The right wing, left wing strut, and vertical stabilizer were substantially damaged during the accident. As designed, the main landing skis are supported by two 5/32 inch braided steel cables and bungee/shock cords. Both ends of the 5/32 inch steel cables terminate with a thimble-eye and a compressed/swaged plain copper oval nicopress sleeve (No. 18-4-P). On the accident airplane, the forward and aft support cables had pulled through their respective nicopress sleeves where the cables attached to the left ski's tip and tail. The nicopress sleeves for the left ski tip and tail attachments were not located during the investigation. However, a visual examination of the remaining nicopress sleeves, located where the support cables attached to the left landing gear leg, appeared to be inadequately compressed. Additionally, a visual inspection of the right main landing ski cables also revealed inadequately compressed nicopress sleeves. The width of the remaining nicopress sleeves, as measured with a dial-caliper, were between 0.440 and 0.446 inch. According to manufacturer specifications, when properly formed, the width of a 5/32 inch nicopress sleeve should be less than 0.395 inch. A test cable eye was fabricated using 5/32 inch braided steel cable and two plain copper oval nicopress sleeves (No. 18-4-P). The first nicopress sleeve was compressed using a proper 5/32 inch swage tool. The other test sleeve was compressed using a larger 3/16 inch swage tool. The width of the properly formed test sleeve, using a 5/32 swage tool, measured 0.383-0.386 inch. The width of the other test sleeve, using a 3/16 swage tool, measured 0.442-0.452 inch. The pilot reported that the airplane was typically equipped with snow skis during thewinter snow seasons. In February 2009, he purchased the main landing skis, Federal Aircraft Works model A-2500A, from a private individual. The skis were purchased used, with an undocumented service history. The skis were acquired as complete assemblies, which included all cables, bungees, brackets, and hardware appropriate for a Stinson model 108-3 installation. The forward and aft support cables were already fabricated and installed on the skis when they were purchased. Additionally, the pilot reported that the support cables had not been repaired or replaced since he owned the skis. On December 14, 2016, the pilot, who was also an aviation mechanic, installed the main landing skis for the 2016/17 winter snow season. According to an airframe logbook entry, the main landing skis were installed per manufacturer's drawing No. 11R955/AB. The accident occurred during the first flight since the skis were installed for the season. ## Aircraft - Registration: [N812C](https://openairdocs.org/deregistered/N812C-2019-08-29), registration cancelled 2019-08-29, S/N 108-3812 (OpenAirDocs) - Reported make and model: STINSON 108-3 - Registry model: [Stinson 108-3](https://openairdocs.org/model/stinson-108-3) (registry code 9230408) (OpenAirDocs) - Registry engine: [Franklin 6A4165 series](https://openairdocs.org/engine/franklin-6a4165-series) (registry code 27025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-3812 - Year built: 1947 - Airframe hours: 4125.51 - Engines: Franklin 6A-335-B1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 11, 2016, 6 hours before - Departed: 24C, Lowell, MI - Destination: Y70, Ionia, MI - Airport: Y70, Ionia County Airport, runway 27, 4,298 × 75 ft, snow - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review May 23, 2015; seat: left; restraint: lap only; flight hours: 2,718 total, 1,884 in this make and model, 25 in the last 90 days, 11 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft overcast - Temperature: 14 °F, dew point 9 °F - Altimeter: 30.26 inHg - Observed at: Y70 ## 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 20161216022149A](https://openairdocs.org/incident/20161216022149A), Dec 16, 2016: Stinson 108-3, Ionia, MI, Substantial damage. On December 16, 2016 at 1045 eastern standard time, a Stinson 108-3 aircraft, N812C, registered to and operated by a private pilot, received substantial damage… ## Docket (6 files) The files NTSB released with the investigation on December 28, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94514. 7.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 674 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447880&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Memorandum of Conversation (Paul Robert Nicholls) (item 2, .PDF, 91 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447881&FileExtension=.PDF&FileName=Memorandum%20of%20Conversation%20(Paul%20Robert%20Nicholls)-Master.PDF - NTSB Cable Examination and Testing (item 3, .PDF, 8 photos, 858 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447882&FileExtension=.PDF&FileName=NTSB%20Cable%20Examination%20and%20Testing-Master.PDF - Main Landing Ski Installation Drawing No. 11R955/AB (item 4, .PDF, 4.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447883&FileExtension=.PDF&FileName=Main%20Landing%20Ski%20Installation%20Drawing%20No.%2011R955%2FAB-Master.PDF - Weather Reports (item 5, .PDF, 102 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447884&FileExtension=.PDF&FileName=Weather%20Reports-Master.PDF - Photos (item 6, .PDF, 2 photos, 343 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447885&FileExtension=.PDF&FileName=Photos-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.