AD 95-18-06 PL SUPERSEDED

95-18-06 Hamilton Standard: Priority Letter issued on August 28, 1995. Docket No. 95-ANE-50. Supersedes Telegraphic AD T95-18-51 and AD 95-05-03, Amendment 39-9170.

Applicability: Hamilton Standard Models 14RF-9, 14RF-19, 14RF-21, and 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15, 14SF-17, 14SF-19, and 14SF-23; and Hamilton Standard/British Aerospace 6/5500/F propellers installed on but not limited to Embraer EMB-120 and EMB 120-RT; SAAB-SCANIA SF 340B; Aerospatiale ATR42-100, ATR42-300, ATR42-320, ATR72; DeHavilland DHC-8-100 series, DHC-8-300 Series; Construcciones Aeronauticas SA (CASA) CN-235 series and CN-235-100; Canadair CL-215T and CL-415; and British Aerospace ATP airplanes. NOTE: This AD applies to each propeller identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For propellers that have been modified, altered, or repaired so that the performance ofthe requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (h) to request approval from the Federal Aviation Administration (FAA). This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any propeller from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent separation of a propeller blade due to cracks initiating in the blade taper bore, that can result in aircraft damage, and possible loss of aircraft control, accomplish the following:

(a) For Hamilton Standard Model 14RF-9 propeller blades, installed on Embraer EMB-120 series aircraft, within the next 10 flight cycles after the effective date of this AD, remove from service propeller blades that have been ultrasonically shear wave inspected in accordance with AD 94-09-06 or AD 95-05-03, removed from service due to crack indications, and subsequently reworked and returned to service. These propeller blades include, but are not limited to, the following serial numbers:

847598 855196 851646 855859 852085 857375 852561 858696 853151 859824 854530 860589 854535 867590 854838 876707 855014 880245 855042

(b) For Hamilton Standard Models 14RF-19, 14RF-21, and 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15, 14SF-17, 14SF-19, and 14SF-23; and Hamilton Standard/British Aerospace 6/5500/F propeller blades, installed on aircraft other than Embraer EMB-120 series aircraft, within the next 10 flight cycles after the effective date of this AD, unless inspected previously in accordance with Telegraphic AD T95-18-51, perform an ultrasonic shear wave inspection for cracks in the blade taper bore of propeller blades that have been ultrasonically inspected in accordance with AD 94-09-06 or AD 95-05-03, removed from service due to crack indications, and subsequently reworked and returned to service. Thereafter, at intervals not to exceed 1,250 flight cycles since last inspection, perform an ultrasonic shear wave inspection for cracks in the blade taper bore of propeller blades. Perform the ultrasonic shear wave inspection in accordance with the Accomplishment Instructions of the following Hamilton Standard Alert Service Bulletins (ASB's), as applicable: No. 14RF-21-61-A68, No. 14SF-61-A88, No. 14RF-19-61-A49, No. 6/5500/F-61-A36; all dated August 25, 1995. Remove cracked propeller blades from service and replace with serviceable parts.

(c) For Hamilton Standard Model 14RF-9 propeller blades, installed on Embraer EMB-120 series aircraft, not affected by paragraph (a) of this AD, perform ultrasonic shear wave inspections in accordance with theAccomplishment Instructions of Hamilton Standard ASB No. 14RF-9-61- A85, dated August 28, 1995. Remove cracked propeller blades from service and replace with serviceable parts:

(1) For propeller blades with 1,250 or more flight cycles since last ultrasonic shear wave inspection on the effective date of this AD, or that have not been ultrasonically shear wave inspected, perform an ultrasonic shear wave inspection for cracks within the next 50 flight cycles after the effective date of this AD.

(2) For propeller blades with less than 1,250 flight cycles since last ultrasonic shear wave inspection on the effective date of this AD, perform an ultrasonic shear wave inspection for cracks within the next 50 flight cycles after the effective date of this AD, or prior to accumulating 1,250 flight cycles, whichever occurs later.

(3) Thereafter, perform repetitive ultrasonic shear wave inspections at intervals not to exceed 1,250 flight cycles since last inspection.

(d) For Hamilton Standard Models 14RF-19, 14RF-21, and 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15, 14SF-17, 14SF-19, and 14SF-23; and Hamilton Standard/British Aerospace 6/5500/F propeller blades; identified by serial number in the ASB's listed in this paragraph, installed on aircraft other than Embraer EMB-120 aircraft, and not affected by paragraph (b) of this AD, perform ultrasonic shear wave inspections in accordance with the Accomplishment Instructions of Hamilton Standard ASB's, as applicable: No. 14RF-21-61-A69, No. 14SF-61-A89, No. 14RF-19- 61-A50, No. 6/5500/F-61-A37; all dated August 28, 1995. Remove cracked propeller blades from service and replace with serviceable parts:

(1) For propeller blades with 1,250 or more flight cycles on the effective date of this AD, or that have not been ultrasonically shear wave inspected, perform an ultrasonic shear wave inspection for cracks within the next 150 flight cycles after the effective date of this AD.

(2) For propeller bladeswith less than 1,250 flight cycles on the effective date of this AD, perform an ultrasonic shear wave inspection for cracks within the next 150 flight cycles after the effective date of this AD, or prior to accumulating 1,250 flight cycles, whichever occurs later.

(3) Thereafter, perform repetitive ultrasonic shear wave inspections at intervals not to exceed 1,250 flight cycles since last inspection.

(e) No ultrasonic shear wave inspections are required for Hamilton Standard Models 14RF- 19, 14RF-21, and 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15, 14SF-17, 14SF-19, and 14SF-23; and Hamilton Standard/British Aerospace 6/5500/F propeller blades, that have been shotpeened in the taper bore during manufacture, and not identified by serial numbers in the ASB's listed in paragraph (b) of this AD.

(f) Propeller blades removed from service in accordance with this AD may not be returned to service.

(g) For the purpose of this AD, a flight cycle is defined as one takeoff andthe next landing of an aircraft.

(h) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Boston Aircraft Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Boston Aircraft Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Boston Aircraft Certification Office.

(i) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

(j) Copies of the applicable service information may be obtained from Hamilton Standard, One Hamilton Road, Windsor Locks, CT 06096-1010; telephone (203) 654-6876. This information may be examined at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA.

(k) Priority Letter AD 95-18-06, issued August 28, 1995, becomes effective upon receipt.

(l) Priority Letter AD 95-18-06 supersedes Telegraphic AD T95-18-51 and AD 95-05-03, Amendment 39-8854.

This priority letter Airworthiness Directive (AD) supersedes an existing Telegraphic AD T95-18-51, that was issued on August 25, 1995, and AD 95-05-03, Amendment 39-9170. Telegraphic AD T95-18-51 was prompted by a report of a Hamilton Standard 14RF-9 propeller blade installed on an Embraer EMB-120 aircraft that separated in flight. The preliminary investigation has revealed that this propeller blade taper bore had been ultrasonically inspected for cracks in accordance with airworthiness directive (AD) 94-09-06, Amendment 39-8894 (59 FR 19127, April 22, 1994). That AD was subsequently superseded by AD 95-05-03, Amendment 39-9170 (60 FR 12663, March 8, 1995). The ultrasonic shear wave inspection determined that the subject propeller blade had crack indications and was removed from service. The propeller was subsequently reworked in accordance with approved data and returned to service. After the propeller was reworked in accordance with approved data, defects remained that were undetectable using current methods. In addition, service experience suggests the possibility that propeller blades installed on Embraer EMB-120 series aircraft may experience higher stress than similar propeller blades installed on other aircraft. Further, blades with the taper bore shotpeened during manufacture and installed on other than Embraer EMB-120 series aircraft do not require ultrasonic shear wave inspection because the shotpeening adds structural integrity. However, the FAA may require inspections on these blades if further investigation warrants. This AD requires ultrasonic shear wave inspection on all Hamilton Standard 14RF-9 propeller blades, and ultrasonic shear wave inspection on certain Hamilton Standard Model 14RF-19, -21, 14SF-5, -7, -11, -15, -17, -19, and - 23; 14SFL11; and Hamilton Standard British Aerospace 6/5500/F propeller blades. This condition, if not corrected, could result in separation of a propeller blade due to cracks initiating in the blade taper bore, that can result in aircraft damage, and possible loss of aircraft control.

The FAA has reviewed and approved the technical contents of the following Hamilton Standard Alert Service Bulletins (ASB's): ASB's No. 14RF-9-61-A85, No. 14RF-19-61-A50, No. 14RF-21-61-A69, No. 14SF-61-A89, and No. 6/5500/F-61-A37, all dated August 28, 1995, that describe procedures for ultrasonic shear wave inspections of the blade taper bores for cracks.

Since an unsafe condition has been identified that is likely to exist or develop on other propellers of this same type design, this priority letter AD will supersede Telegraphic AD T95-18-51 and AD 95-05-03 to require: (1) removal from service of certain Hamilton Standard Model 14RF-9 propeller blades installed on Embraer EMB-120 aircraft; (2) an ultrasonic shear wave inspection for cracks on certain reworked propeller blades installed on aircraft other than the Embraer EMB-120; and (3) requires repetitive ultrasonic shear wave inspections ofall Hamilton Standard Model 14RF-9 propeller blades and repetitive ultrasonic shear wave inspections on all unshotpeened and certain shotpeened Hamilton Standard Models 14RF-19, -21; 14SF-5, -7, -11, -15, -17, -19, -23; 14SFL11; and Hamilton Standard/British Aerospace 6/5500/F propeller blades regardless of aircraft installation. Propeller blades removed from service in accordance with this AD may not be returned to service.

This rule is issued under 49 U.S.C. Section 44701 (formerly section 601 of the Federal Aviation Act of 1958) pursuant to the authority delegated to me by the Administrator, and is effective immediately upon receipt of this priority letter.

Frank Walsh, Aerospace Engineer, Boston Aircraft Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (617) 238- 7158, fax (617) 238-7199.