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Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns

FAA William J. Hughes Technical Center-Christopher Dumont
AMA-NASA Langley Research Center-Justin Strickland, Patricia Hunt
Published 2019-06-10 by SAE International in United States
NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding of high ice water content (HIWC) and develop onboard weather radar processing techniques to detect regions of HIWC ahead of an aircraft to enable tactical avoidance of the potentially hazardous conditions. Both HIWC RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory equipped with a Honeywell RDR-4000 weather radar and in-situ microphysical instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results.The first campaign was conducted in August 2015 with a base of operations in Ft. Lauderdale, Florida. Ten research flights were made into deep convective systems that included Mesoscale Convective Systems (MCS) near the Gulf of Mexico and Atlantic Ocean, and Tropical Storms Danny and Erika near the Caribbean Sea. The radar and in-situ measurements from these ten flights were analyzed…
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Determination of the Operational Environment of the Propeller Blades on Beech 1900D Aircraft

FAA William J. Hughes Technical Center-T. DeFiore, C. Nguyen
FAA Engine and Propeller Directorate-J. E. Turnberg
Published 2008-08-19 by SAE International in United States
Data obtained from digital flight data recorders are used to assess the actual operational environment of propellers on a fleet of Beech 1900D aircraft in commuter role. Information is given on various aerodynamic parameters as well as those pertaining to engine and propeller usage. The takeoff rotation has been identified as the most demanding phase of flight in terms of unsteady loads exerted on the propeller blades. Special attention is paid to ground operations.
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Operational Loads Monitoring of a Fleet of Beech 1900D Aircraft

SAE International Journal of Aerospace

FAA William J. Hughes Technical Center-Thomas DeFiore
Wichita State University-Linda K. Kliment, Richard B. Bramlette, Kamran Rokhsaz
  • Journal Article
  • 2008-01-2232
Published 2008-08-19 by SAE International in United States
Presented here are analyses and statistical summaries of data collected from 11,299 flight operations recorded on 6 BE-1900D aircraft during routine commuter service over a period of three years. Basic flight parameters such as airspeed, altitude, flight duration, etc. are shown in a form that allows easy comparison with the manufacturer's design criteria. Lateral ground loads are presented for ground operations. Primary emphasis is placed on aircraft usage and flight loads. Maneuver and gust loads are presented for different flight phases and for different altitude bands. In addition, derived gust velocities and various coincident flight events are shown and compared with published operational limits. The data presented in this form should allow an objective comparison of the existing certification and design criteria with actual usage data, thereby affording aircraft manufacturer and operators a better understanding and control of those factors that influence the structural integrity of commuter aircraft.
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The Fatigue Behavior of Fastener Joints

SAE International Journal of Aerospace

FAA William J. Hughes Technical Center-M. Shiao
National Institute for Aviation Research-C. Gomez
  • Journal Article
  • 2008-01-2259
Published 2008-08-19 by SAE International in United States
The fatigue behavior of Hilok fastener joints under constant amplitude loading has been investigated experimentally. The effects of load transfer in an unbalanced joint configuration was characterized in terms of a stress severity factor relative to the open-hole configuration. The experimental data indicates that the clamp-up forces dominate the performance of fastener joints with the open-hole fatigue life being the lower bound at the stress levels investigated. The failure modes were observed to transition from a net-section type failure across the minimum section to a fretting induced failure at some distance from the hole. The experimental data has been used to develop stress severity factors to be used as a measure of the fatigue quality of the fastener joints.
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Reliability-Based Damage Tolerance Methodology for Rotorcraft Structures

FAA William J. Hughes Technical Center-Michael Shiao
Applied Research Associates-Justin Y-T. Wu, Youngwon Shin
Published 2004-03-08 by SAE International in United States
This paper presents a reliability-based damage tolerance (RBDT) methodology that employs a systematic approach for probabilistic fracture-mechanics damage tolerance analysis subject to uncertainties in initial flaw, probability of detection (POD) and other random variables. By integrating a basic probabilistic analysis engine, a finite element analysis code, and a fatigue crack analysis code, the RBDT methodology has been implemented in a prototype software and used to assess the applicability and benefits of applying RBDT methodology to supplement the safe-life and deterministic-based damage tolerance design methods.A new efficient and accurate probabilistic method, built on a two-stage conditional importance sampling approach, is presented. The first stage computes risk, without inspection, using the most probable point (MPP)-based importance-sampling technique combined with a new error-checking method. The second stage computes risk, with inspection, by simulating inspection and maintenance effects using the samples generated from the Stage 1 failure domain. The error-checking procedure addresses the major shortcoming in the MPP-based approximation methods and leads to a robust and efficient sampling method.For inspection optimization and maintenance planning, this paper proposes a strategy…
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