# NTSB CEN18LA292: Grumman AA5, N74420, Brazoria, TX, July 23, 2018 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 23, 2018, 12:15 local (17:15 UTC) - Place: Brazoria, TX · Clemens Correctional Institution - Coordinates: 28.984722, -95.539169 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.9847&lon=-95.5392&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - Houston FSDO - NTSB case key (mKey): 97860 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN18LA292 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97860/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97860 - Page: https://openairdocs.org/ntsb/CEN18LA292 ## Probable cause The propeller blade separation due to a fatigue fracture. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Propeller system: propeller blade section](https://openairdocs.org/ntsb-findings/01046111): Aircraft › Aircraft propeller/rotor · Fatigue/wear/corrosion (probable cause); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=3960105), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md) - [Propeller system: propeller blade section](https://openairdocs.org/ntsb-findings/01046111): Aircraft › Aircraft propeller/rotor · Failure (probable cause); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md?model=3960105), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/01046111/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Grumman American Avn. AA-5B, 2 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=3960105), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Grumman American Avn. AA-5B, 7 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3960105), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The student pilot and his flight instructor were conducting a local instructional flight when the airplane began to shake violently. A reduction of engine power revealed that the one of the propeller blades had separated about midspan. The flight instructor took control of the airplane and completed an uneventful forced landing in a nearby field. A postaccident examination revealed several fractured engine mounts. A laboratory examination of the propeller revealed that about one-half of one blade had fractured. Further examination of the flat portion of the fracture surface revealed a pattern of crack arrest lines and striations that were consistent with fatigue cracking. The pattern of crack arrest lines indicated that the fatigue cracking emanated from the trailing edge tip of the blade. Damage to the fracture surface at the trailing edge tip of the blade obscured the exact initiation point of the fatigue cracking. The propeller had accumulated about 4,499 hours since its last overhaul, and about 11 hours since it was last examined during an annual inspection. ## Factual narrative On July 23, 2018, about 1215 central daylight time, a Grumman AA-5B, N74420, was substantially damaged while maneuvering near Brazoria, Texas. The flight instructor and student pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the student pilot, the airplane began to shake violently while he practiced basic-attitude maneuvers under simulated instrument meteorological conditions. A reduction of engine power revealed that the one of the propeller blades had separated about midspan. The flight instructor took control of the airplane and completed an uneventful forced landing in a nearby field. A postaccident examination revealed several fractured engine mounts. The two-blade propeller, a McCauley Propeller Systems model No. 1A170/FFA7563, serial No. P77410, was examined at the National Transportation Safety Board Materials Laboratory in Washington, D.C. About one-half of one blade had separated and was not located during the investigation. The fracture surface was flat from the trailing edge through roughly two-thirds of the chord length, before angling from the center outwards adjacent to the blade surface. Further examination of the flat portion of the fracture surface revealed a pattern of crack arrest lines and striations that were consistent with fatigue cracking. The pattern of crack arrest lines indicated that the fatigue cracking emanated from the trailing edge tip of the blade. Damage to the fracture surface at the trailing edge tip of the blade obscured the exact initiation point of the fatigue cracking. According to the propeller logbook, the most recent propeller inspection was completed in conjunction with an annual inspection on November 1, 2017, at which time the propeller had accumulated 4,488 hours since its last overhaul. The airplane had been flown about 11 hours since the last annual inspection. ## Aircraft - Registration: [N74420](https://openairdocs.org/deregistered/N74420-2021-10-30), registration cancelled 2021-10-30, S/N AA5B-0222, built 1975 (OpenAirDocs) - Reported make and model: Grumman AA5 (B) - Registry model: [Grumman American Avn. AA-5B](https://openairdocs.org/model/grumman-american-avn-aa-5b) (registry code 3960105) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: AA5B-0222 - Year built: 1975 - Airframe hours: 4499 - Engines: Lycoming O-360-A4K 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Rjm-Av8, LLC - Registered owner: Rjm-Av8, LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 1, 2017, 11 hours before - Departed: LVJ, Pearland, TX - Destination: Same as departure - Equipment: Stall warning system, Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 54; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 11, 2018; seat: right; restraint: 3-point; flight hours: 968.4 total, 18.6 in this make and model, 855.2 as pilot in command, 101 in the last 90 days, 24.8 in the last 30 days, 1.9 in the last 24 hours - Student pilot; age 40; injuries: none; student; medical: class 2; seat: left; restraint: 3-point; flight hours: 24 total, 7.8 in this make and model, 0 as pilot in command, 0.75 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 91 °F, dew point 73 °F - Altimeter: 29.92 inHg - Observed at: LBX, 9 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 20180723017709A](https://openairdocs.org/incident/20180723017709A), Jul 23, 2018: Grumman American Avn. Corp. AA-5B, Brazoria, TX, Substantial damage. During an instrument training flight aircraft started to shake violently. Pilot pulled the throttle out to idle and noticed a missing propeller blade. Aircraft… ## Docket (6 files) The files NTSB released with the investigation on April 1, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97860. 23.5 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 417 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11749005&FileExtension=pdf&FileName=01%20-%20Pilot%20Report_Redacted-Rel.pdf - Materials laboratory factual report (item 2, PDF, 6 pages, 9 photos, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11748196&FileExtension=pdf&FileName=02%20-%20Materials%20Lab%20Factual%20Report%20(CEN18LA292)-Rel.pdf - Airframe logbook (item 3, PDF, 10 pages, 14.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11748878&FileExtension=pdf&FileName=03%20-%20Airframe%20Logbook_Redacted-Rel.pdf - Engine logbook (item 4, PDF, 17 pages, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11748257&FileExtension=pdf&FileName=04%20-%20Engine%20Logbook_Redacted-Rel.pdf - Propeller logbook (item 5, PDF, 12 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11748819&FileExtension=pdf&FileName=05%20-%20Propeller%20Logbook_Redacted-Rel.pdf - Photo (item 6, PDF, 1 page, 217 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11748888&FileExtension=pdf&FileName=07%20-%20Photos-Rel.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.