# NTSB GAA17CA179: Burkhart Grob G 109B, N109FH, Mokuleia, HI, March 8, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: March 8, 2017, 13:30 local (23:30 UTC) - Place: Mokuleia, HI - Coordinates: 21.579444, -158.202499 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=21.5794&lon=-158.2025&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report June 7, 2017 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 94843 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA179 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94843/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94843 - Page: https://openairdocs.org/ntsb/GAA17CA179 ## Probable cause The failure of the upper rudder hinge during flight due to severe corrosion. Contributing to the accident were the pilot’s inadequate preflight inspection and the lack of an annual inspection. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-findings/02061510/cases.md?model=1660205), [All aircraft, 551 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md) - [Flight control system: rudder control system](https://openairdocs.org/ntsb-findings/01022720): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-findings/01022720/cases.md?model=1660205), [All aircraft, 93 cases](https://openairdocs.org/ntsb-findings/01022720/cases.md) - [Flight control system: rudder control system](https://openairdocs.org/ntsb-findings/01022720): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-findings/01022720/cases.md?model=1660205), [All aircraft, 93 cases](https://openairdocs.org/ntsb-findings/01022720/cases.md) - [Environmental issues](https://openairdocs.org/ntsb-findings/03020000): Environmental issues › Physical environment · Effect on equipment; cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-findings/03020000/cases.md?model=1660205), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/03020000/cases.md) - [Knowledge: knowledge of regulatory reqs](https://openairdocs.org/ntsb-findings/02032025): Personnel issues › Experience/knowledge · Pilot; cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-findings/02032025/cases.md?model=1660205), [All aircraft, 5 cases](https://openairdocs.org/ntsb-findings/02032025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Burkhart Grob G-109B, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=1660205), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The pilot, who was the owner of the powered glider, reported that, during the preflight, he "did not note any anomalies or irregular motion of the control surfaces." He added that, during a turn in cruise flight, the rudder pedals "abruptly became unusual." He looked to the rear of the powered glider and saw that the rudder had detached from the top of the vertical stabilizer. He added that the adverse yaw was "mild," so he continued to land. During the landing roll, the rudder separated from the empennage. Photographs provided by the Federal Aviation Administration showed extensive corrosion on the rudder hinges. The upper hinge showed a clean fracture surface on both the rudder and vertical stabilizer sides of the hinge. The pilot reported that he has an outdoor tie-down space on the airport where he parks the powered glider. The airport is located in a marine environment, less than 1/2 mile from the Pacific Ocean. The flight manual section titled, "Daily Inspections," stated, in part, Prior to flight operations the following visual exterior checks have to be performed… 5. Tail unit • Proper installation • Securely locked • Control connections locked • Freedom of movement • Damage • Pitot pressure tube (vertical fin) checked, cover remove A review of maintenance records revealed that the most recent annual inspection was completed about 14 months before the accident. The most recent inspection performed on the powered glider was a 6,000-hour "Extension of Life Time" inspection, which was performed about 9 months before the accident. In the 6,000-hour inspection checklist, all line items were initialed "satisfactory" except for the "visual check for any decay" line items for the aileron, controls in the fuselage, elevator/trim tab, and rudder, which were left uninitialed. The mechanic who performed the most recent annual inspection and the 6,000-hour "Extension of Life Time" inspection reported that he did not notice anything abnormal during either inspection and that, during the 6,000-hour inspection, he did not carry his initials down to the "visual check for any decay" line items but that they were performed and that the condition looked "satisfactory." He added that he believed the corrosion was responsible for the upper rudder hinge failure and that it is not uncommon for that amount of corrosion to form between the time of the most recent inspection and the accident flight. He recommended that the glider should have been inspected more often and rinsed with water daily to remove any salt residue from ocean spray. In followup e-mail correspondence, the pilot reported that he believed that, during the "Extension of Life Time" inspection, all inspections had been renewed. He added that he learned after the accident that the annual inspection had not been performed. ## Factual narrative The pilot, who was the owner, of the powered glider reported that during the preflight he "did not note any anomalies or irregular motion of the control surfaces". He added that during a turn in cruise flight the rudder pedals "abruptly became unusual". He looked to the rear of the powered glider and saw that the rudder had detached from the top of the vertical stabilizer. He further added that the adverse yaw was "mild", so he continued to land. During the landing roll, the rudder separated from the empennage. Photographs of the rudder hinges provided by the FAA showed extensive corrosion on the hinges. The upper hinge showed a clean fracture surface on both the rudder and vertical stabilizer sides of the hinge. The pilot reported that he has an outdoor tie-down space on the airport where he parks the powered glider. The airport is located in a marine environment, less than one-half mile from the Pacific Ocean. The flight manual section Titled "Daily Inspections" stated in part: "Prior to flight operations the following visual exterior checks have to be performed… 5. Tail unit • Proper installation • Securely locked • Control connections locked • Freedom of movement • Damage • Pitot pressure tube (vertical fin) checked, cover remove" A review of maintenance records revealed that the most recent annual inspection was completed about 14 months before the accident. The most recent inspection performed on the powered glider was a 6000-hour "Extension of Life Time" inspection, which was performed about 9 months prior to the accident. In the 6000-hour inspection checklist, all line items were initialed "satisfactory" with the exception of the "visual check for any decay" line items for the aileron, controls in the fuselage, elevator/trim tab, and rudder, which were left un-initialed. The mechanic who performed the most recent annual inspection and the 6000-hour "Extension of Life Time" inspection reported that he did not notice anything abnormal during either inspection and that during the 6000-hour inspection he did not carry his initials down to the "visual check for any decay" line items, but they were performed and the condition looked "satisfactory". He added that he believed the corrosion was responsible for the upper rudder hinge failure and that it is not uncommon for that amount of corrosion to form between the time that the most recent inspection was performed and the accident flight. He recommended that the glider should have been inspected more often and rinsed with water daily to remove any salt residue from ocean spray. In a follow up email correspondence, the pilot reported that he believed that during the "Extension of Life Time" inspection, all inspections had been renewed. He added that only after the accident had he learned that the annual inspection had not been performed. ## Aircraft - Registration: [N109FH](https://openairdocs.org/aircraft/N109FH), registered now, S/N 6367 (OpenAirDocs) - Reported make and model: BURKHART GROB G 109B (UNDESIGNAT) - Registry model: [Burkhart Grob G-109B](https://openairdocs.org/model/burkhart-grob-g-109b) (registry code 1660205) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Glider - Serial number: 6367 - Year built: 1985 - Airframe hours: 5677.6 - Engines: Grob 2500 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Utility - Last inspection: Annual, January 15, 2016 - Departed: HDH, Mokuleia, HI - Destination: HDH, Mokuleia, HI - Airport: HDH, Dillingham Airfield, runway 08, 9,007 × 75 ft, asphalt - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review February 23, 2017; seat: left; flight hours: 1,140 total, 326 in this make and model, 1,087 as pilot in command, 19 in the last 90 days, 5 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 60° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 63 °F - Altimeter: 30.01 inHg - Observed at: PHHI, 11 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 20170308002989A](https://openairdocs.org/incident/20170308002989A), Mar 8, 2017: Burkhart Grob G-109B, Mokuleia, HI, Substantial damage. The pilot departed hdh to conduct ridge soaring near the airfield. After climbing to altitude the pilot shut the engine off and flew several passes along the… ## Docket (6 files) The files NTSB released with the investigation on May 2, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94843. 5.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 263 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453765&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Daily Inspection Checklist (item 2, .PDF, 397 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40451668&FileExtension=.PDF&FileName=Daily%20Inspection%20Checklist-Master.PDF - Maintenance Records (item 3, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40451669&FileExtension=.PDF&FileName=Maintenance%20Records-Master.PDF - 6000 Hour Extension of Life Time Inspection (item 4, .PDF, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40451670&FileExtension=.PDF&FileName=6000%20Hour%20Extension%20of%20Life%20Time%20Inspection-Master.PDF - Follow Up Email Correspondence with Pilot (item 5, .PDF, 174 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40451671&FileExtension=.PDF&FileName=Follow%20Up%20Email%20Correspondence%20with%20Pilot-Master.PDF - Accident Photos (item 6, .PDF, 4 photos, 741 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40451672&FileExtension=.PDF&FileName=Accident%20Photos-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.