![]() They say:Īn occurrence was reported of fan blade failure on a CFM56-7B engine. UPDATE 8 March 2018: The European Aviation Safety Agency ( EASA) has issued Proposed Airworthiness Directive (PAD) 17-132R1 for a one-time inspection of certain CFM56-7 blades, involving an ultrasonic inspection of each one affected, within nine months. ![]() They said 109 of its engines their engine were affected (at the time) and note they do not track fan blade cycles by serial number Southwest opposed a CFM proposal to reduce the FAA compliance time. UPDATE 10 October 2017: Southwest was one of a number of respondees to the FAA NPRM consultation. UPDATE 25 August 2017: The FAA issued a Notice of Proposed Rule Making for an AD for comment with 15,000 cycles since last shop visit as the applicability criteria. įuture work will include 3-D measurements of the contact areas of all the blades, a non-destructive examination of the blade surfaces for cracks, and a review of the engine maintenance records. CFM International is a joint venture between GE Aviation and Safran Aircraft Engines. The French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile has appointed an accredited representative who is supported by a technical advisor from Safran Aircraft Engines. Parties to the investigation include the Federal Aviation Administration, Southwest Airlines, the Southwest Airlines Pilots Association, and CFM International. The NTSB’s Tim LeBaron is Investigator-in-Charge. The Flight Data Recorder ( FDR) and the Cockpit Voice Recorder ( CVR) have been down loaded by the NTSB. The First Accident Flight 27 August 2016: N766SW (Pensacola) The out of balance forces resulted in failure of the inlet structure. The NTSB originally called these uncontained failures, though the fan blades did not exit radially (the true definition of uncontained) but instead axially (i.e. This was Southwest’s first passenger fatality ever and the first Part 121 passenger airline fatality since February 2009 (although all 7 crew died in a B747F crash at Bagram, Afghanistan in April 2013). In that case debris penetrated a cabin window aft of the wing and one passenger is confirmed to have died (early reports suggest they had been partly sucked through the window). The US National Transportation Safety Board ( NTSB) has issued a press release, in advance of a preliminary report, on a fan blade off (FBO) occurrence to Boeing 737-700 N766SW operating Southwest Airlines Flight 3472, from New Orleans, Louisiana to Orlando, Florida on 27 August 2016.Ī second, seemingly very similar FBO event occurred to N772SW operating Flight 1380 from New York-La Guardia, NY to Dallas-Love Field, Texas on 17 April 2018. This study, therefore, concluded that the inclusion of in-plane residual stresses in fatigue life estimates is significant for turbine blades operating at short flight time intervals with less effect on long mission operations.‘Uncontained’ CFM56-7 FBO Failures: Southwest B737-700s 27 August 2016 & 17 April 2018 (UPDATED) As the flight time increases, the residual stress influence decreases due to stress relaxation. The results acquired from this study showed an average residual stress contribution of 70% towards the fatigue life estimated cycles to failure of engines undertaking short flight missions. Subsequently, a fatigue software (Fe-safe) was used to determine the fatigue behavior of the bladed disk while taking into consideration the in-plane residual stresses. In order to incorporate these residual stresses into engine operating conditions, an ABAQUS Finite Element Analysis (FEA) was conducted to define stresses which are effective during operation. The samples were subsequently heat-treated in order to mimic the operating conditions of the engine and then evaluated experimentally for the presence of residual stresses. This was achieved by manufacturing test samples using Additive Manufacturing (AM). The aim of this study is to investigate the significance of residual stresses in fatigue analyses of micro gas turbine blades in order to attain accurate fatigue life estimates such studies have not been adequately investigated.
0 Comments
Leave a Reply. |