# NTSB ANC98LA164: Grumman S2F-1, N8115V, Wasilla, AK, September 24, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 24, 1998, 12:40 local (20:40 UTC) - Place: Wasilla, AK - Location: 61.5720° N, 149.5396° W: Placed by OpenAirDocs at WASILLA (IYS), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=61.5720&lon=-149.5396&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 16, 2001 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 44042 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC98LA164 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/44042/pdf - Page: https://openairdocs.org/ntsb/ANC98LA164 ## Probable cause The failure of the recently overhauled right brake seal resulting in a total loss of brake fluid, failure of the right brake system, and subsequent inability of the pilot to utilize the brake. A contributing factor was the soft terrain. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - hydraulic system,seal - failure,total (cause) - maintenance,overhaul - performed, other maintenance personnel - fluid,hydraulic - loss,total - landing gear,normal brake system - failure,total - Loss of control - on ground/water, landing - roll - terrain condition - soft (contributing factor) - directional control - not possible, pilot in command - Nose gear collapsed, landing - roll ## Analysis During the landing roll, the right brake seal failed on the experimental category, ex-military airplane, releasing the hydraulic fluid and subsequently rendering the brake unusable. The airplane encountered soft earth as it began to drift left, and ultimately departed the left side of the 3,700 feet long by 75 feet wide gravel runway. The nose gear then collapsed. The right brake system had been overhauled and the right brake seal replaced 15 hours prior to the accident. ## Factual narrative On September 24, 1998, about 1240 Alaska daylight time, a Grumman S2F-1 airplane, N8115V, sustained substantial damage when it departed runway 21 during landing at the New Wasilla airport, Wasilla, Alaska. The solo airline transport pilot was not injured. The airplane was owned and operated by the pilot under 14 CFR Part 91 as a local, personal flight. The airplane was being operated under an FAA letter of authorization, leading to an experimental category airworthiness certificate. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot told the NTSB investigator-in-charge during a telephone interview on September 29, and wrote in his NTSB Pilot / Operator report, that during landing the right brake failed and the airplane began to drift to the left. The pilot said that soft earth on the left side of the runway compounded the left drift, and that differential power did not swing the nose of the airplane back to the right. The airplane departed the left side of the 3,700 feet long by 75 feet wide gravel runway, and the nose landing gear collapsed. Subsequent inspection of the airplane by an FAA Flight Standards District Office inspector revealed that the right brake seal failed, releasing the hydraulic fluid. A review of records showed that the right main landing gear had been overhauled, and the right brake seal replaced on June 8, 1998, at 7,363 airframe total hours, 15 hours prior to the accident. A review of work orders submitted by the overhaul facility listed the following repairs (in part): Remove R/H Wheel & Repair Leak 1.8 hours Overhaul Brakes 3.3 hours Install Tire & Set Brakes 0.8 hours Install R/H Brake 2.2 hours Install Brakes 4.3 hours ## Aircraft - Registration: N8115V (not matched to a registry record) - Reported make and model: Grumman S2F-1 - Category: Airplane - Serial number: 144725 - Airframe hours: 7378 - Engines: Wright R-1820-82B 1475 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Terrance M. Cosgrove - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Continuous airworthiness, June 8, 1998, 15 hours before - Departed: IYS, NEW WASILLA, AK - Destination: IYS - Airport: IYS, New Wasilla, runway 21, 3,700 × 75 ft, gravel ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 10,100 total, 32 in this make and model, 4,500 as pilot in command, 210 in the last 90 days, 78 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 48 °F - Altimeter: 29.00 inHg ## 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 19980924026949A](https://openairdocs.org/incident/19980924026949A), Sep 24, 1998: Grumav S2F1, Wasilla, AK, Substantial damage. (-23) During landing roll under heavy braking there was a loss of braking on the right hand side, differential power application failed to correct the drift to… 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.