Pratt & Whitney

Document ID: FAA-2010-0398-0006
Document Type: Public Submission
Agency: Federal Aviation Administration
Received Date: July 26 2010, at 12:00 AM Eastern Daylight Time
Date Posted: July 27 2010, at 12:00 AM Eastern Standard Time
Comment Start Date: April 26 2010, at 12:00 AM Eastern Standard Time
Comment Due Date: July 26 2010, at 11:59 PM Eastern Standard Time
Tracking Number: 80b20c76
View Document:

This is comment on Rule

Airworthiness Standards; Rotor Overspeed Requirements

View Comment

The proposed rule as written will create an un-harmonized situation with EASA SC-E Section 840 Rotor Integrity which is contrary to the stated intent of the proposed FAA rule to harmonize with the EASA rule. As written section 33.77(c) would require overspeeds resulting from multiple failures to be assessed unless they occur at a rate of less than 10E-09. The current EASA rule (CS-E 840(c) ) requires these to be assessed unless they can be shown to be "Extremely Remote" which is defined as no gretaer than 10E-07. This definition is also consistent with FAR 33.75 Safety Analysis so the proposed rule as written would be inconsistent with existing FAR 33.75. Also the rate in the proposed 33.27 (c) is quoting the rate in terms of "per flight" whereas the existing convention for EASA CS-E and FAR 33 is "per engine flight hour".