Lycoming O-360, IO-360 SAP Crankshaft AD

[Navy79]

Saw this on Beech Talk.  NRPM comment period through 3/16/20.

https://www.federalregister.gov/documents/2020/01/29/2020-01414/airworthiness-directives-superior-air-parts-inc-sap-engines-and-lycoming-engines-reciprocating

[bradp]

Seems like it’s the superior crank.  I can’t tell if it’s limited to their branded engines or they are Lycoming OEM or just PMA replacement .  Doesn’t seem to give serial numbers.  Limited to cranks produced in 2012 and 2014- 115 certificated aircraft. 
 

https://www.aopa.org/news-and-media/all-news/2020/february/12/faa-considers-superior-air-parts-crankshaft-assembly-ad

[vorlon1]

Some relevant info copied from the document:

This AD applies to the reciprocating engine models identified in paragraphs (c)(1) and (2) of this AD with a Superior Air Parts, Inc. (SAP) crankshaft assembly, part number (P/N) SL36500-A20 or P/N SL36500-A31, with serial numbers 82976-01; 82976-02; SP12-0003 through SP12-0089, inclusive; SP13-0034 through SP13-0150, inclusive; or SP14-0151 through SP14-0202, inclusive; installed.

(1) With SAP crankshaft assembly, P/N SL36500-A20, installed:

(i) SAP Model IO-360-series and O-360-series reciprocating engines.

(ii) Lycoming Engines (Lycoming) Model IO-360-B2F, IO-360-L2A, O-360, O-360-A2A, O-360-A2D, O-360-A2E, O-360-A2F, O-360-A2G, O-360-B2A, O-360-C2A, O-360-C2C, O-360-C2D, O-360-C2E, O-360-D2A, and O-360-D2B reciprocating engines.

(2) With SAP crankshaft assembly, P/N SL36500-A31, installed:

(i) SAP Model IO-360-series and O-360-series reciprocating engines.

(ii) Lycoming Model AEIO-360-H1A, IO-360-B1A, IO-360-B1B, IO-360-B1D, IO-360-B1E, IO-360-B1F, IO-360-M1A, O-360, O-360-A1A, O-360-A1C, O-360-A1D, O-360-A2A, O-360-C1A, O-360-C1G, O-360-C1C, O-360-C1E, and O-360-C1F reciprocating engines.

Note 1 to paragraph (c) of this AD:

This SAP crankshaft assembly may be installed as a replacement part under parts manufacturer approval on the affected Lycoming engines.

[tigers2007]

Terrifying news for 115 engine owners. $15k a pop is their estimate to replace? Yuck. A new crank itself costs 9 AMU’s? I wonder what innovation in the alloy process made them change the formula that resulted in the “white powder”.

[EricJ]

On 2/15/2020 at 5:45 AM, tigers2007 said:

Terrifying news for 115 engine owners. $15k a pop is their estimate to replace? Yuck. A new crank itself costs 9 AMU’s? I wonder what innovation in the alloy process made them change the formula that resulted in the “white powder”.

Sounds like it's not the alloy but the nitride case-hardening process done on the journals.

"The FAA's analysis of the process used to manufacture the failed assemblies identified that gaseous nitrocarburization resulted in excessive residual white layer forming on the assemblies. This white layer is brittle and can lead to spalling or fatigue cracking of the crankshaft assembly as a result of the normal mechanical loads during engine operation. The FAA's analysis concluded that all three SAP crankshaft assembly failures were the result of this fatigue cracking."