Electromechanical Actuator Cooling Fan Reliability Analysis And Safety Improvement

Abstract

The aircraft electromechanical actuator (EMA) cooling fan is a critical component because an EMA failure caused by overheating could lead to a catastrophic failure in aircraft. Fault tree analysis (FTA) is used to access the failure probability of EMA fans with the goal of improving their mean time to failure (MTTF) from ∼O(5×104) to ∼ O(2.5×109) hours without incurring heavy weight penalty and high cost. The dual-winding and dual-bearing approaches are analyzed and a contra rotating dual-fan design is proposed. Fan motors are assumed to be brushless direct current (BLDC) motors. To have a full understanding of fan reliability, all possible failure mechanisms and failure modes are taken into account. After summarizing the possible failure causes and failure modes of BLDC fans by focusing on each failure mechanism, the life expectancy of fan ball bearings based on a major failure mechanism of lubricant deterioration is calculated and compared to that provided in the literature. The advantages and disadvantages of the three fault-tolerant cases are discussed. Finally, measures to quantify a fan's reliability are recommended and the method to estimate MTTF by Weibull distribution is provided.

Publication Date

9-20-2016

Publication Title

SAE Technical Papers

Volume

2016-September

Issue

September

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.4271/2016-01-1997

Socpus ID

85016479720 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85016479720

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