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2011-18-09: Crankshaft failure

FAA order 2011-18-09 is an airworthiness directive in force since September 29, 2011. The FAA's subject line: Crankshaft failure. It names the Lycoming IO-720-A1B engine: about 8 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: engine.

What it applies to as the FAA lists it

Kind of product
Engine
Makes
Textron Lycoming, AVCO Corporation
Models
IO-720-A1B
Engine series
Lycoming IO-720-A1B 8 aircraft

Dates and paperwork

In force since
September 29, 2011
Published
September 14, 2011 (signed August 18, 2011)
Docket
FAA-2011-0604
Status
Current
The FAA's document
Read the order on the FAA's site

The FAA's summary their words, unchanged

We are adopting a new airworthiness directive (AD) for certain model IO-720-A1B Lycoming Engines reciprocating engines. This AD requires a crankshaft inspection for certain parts that may be installed. This AD was prompted by the failure of a crankshaft due to incorrect parts installed. We are issuing this AD to prevent engine crankshaft failure and damage to the airplane.

The order itself the regulatory text, as published

Show the full text (3,228 characters)
Adoption of the Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39--AIRWORTHINESS DIRECTIVES 0 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. Sec. 39.13 [Amended] 0 2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD): 2011-18-09 Lycoming Engines (formerly Textron Lycoming Division, AVCO Corporation): Amendment 39-16791; Docket No. FAA-2011-0604; Directorate Identifier 2011-NE-21-AD. Effective Date (a) This AD is effective September 29, 2011. Affected ADs (b) None. Applicability (c) This AD applies to Lycoming Engines reciprocating engines, model IO-720-A1B, serial number L-1457-54A and serial number L-1458- 54A. These engines were last known to be installed in a Beech U-8F (Queen Air) N51779 and operating in the southern U.S. and Mexico.Unsafe Condition (d) This AD was prompted by the failure of a crankshaft due to incorrect parts installed. We are issuing this AD to prevent engine crankshaft failure and damage to the airplane. Compliance (e) Comply with this AD before further flight after the effective date of this AD, unless already done. Crankshaft Inspection (f) Remove the four cylinders from one side of the engine. Guidance on removing the cylinders can be found in the Lycoming Engines Overhaul Manual. (g) Each counterweight has two rollers that should be held in place by washers, Lycoming part number (P/N) 71907. The washers can be identified as having three holes each, with a diameter of 0.185 inch. These washers are located at the front and rear of each counterweight for a total of four P/N 71907 washers per counterweight. The eight counterweights are located at the top and bottom of each crankshaft cheek, totaling 32 washers per crankshaft. (h) Rotate the crankshaft to inspect the holes in washers at the front and rear of each counterweight as well as the top and bottom of each cheek. (i) If each hole, in each of the 32 washers, measures 0.185 inch, then no further action is required. Reinstall the cylinders and test the engine. Guidance on reinstalling and testing can be found in the Lycoming Engines Overhaul Manual. (j) If any of the 32 washers have one or more holes that do not measure 0.185 inch, then remove the crankshaft assembly and replace it with a serviceable crankshaft assembly. Scrap the non-conforming crankshaft. Special Flight Permits (k) Special flight permits are authorized only if the engine has less than 400 hours time since overhaul. Alternative Methods of Compliance (AMOCs) (l) The Manager, New York Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD if requested using the procedures found in 14 CFR 39.19. Related Information (m) For more information about this AD, contact Norm Perenson, Aerospace Engineer, New York Aircraft Certification Office, FAA, Engine & Propeller Directorate, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7337; fax: 516-794-5531; e-mail: Norman.perenson@faa.gov. Material Incorporated by Reference (n) None.

Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of October 5, 2026. Connections as data: /graph/directive/2011-18-09.json · aircraft systems.