FAA SPECIAL AIRWORTHINESS
Aviation Safety INFORMATION BULLETIN
SAIB: NE-16-19
SUBJ: Turbine Engine Compressor Section – Stator Nozzle Distress Date: July 22, 2016
This is information only. Recommendations aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) alerts you, owners, operators, and
certificated repair or maintenance facilities of airplanes equipped with Honeywell Inc. (Honeywell)
TPE331-10 and TPE331-11 series turboprop engines, to 1st stage turbine blade failures.
At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness
directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.
Background
We have received reports of 21 1st stage turbine blade failures on Honeywell TPE331-10 and -11
series engines from October, 1997 to November, 2013. These failures caused 15 in-flight shutdown
events resulting in moderate to severe turbine damage. Of the 21 blade failures, 9 involved 1st stage
turbine nozzle distress and nozzle vane burn-through. Nozzle vane burn-through creates a one-per-rev
excitation to the 1st stage turbine blades, which contributes to premature blade failures.
The Accomplishment Instructions of Honeywell Service Bulletin (SB) TPE331-73-0284, dated
November 3, 2014, recommends a borescope inspection (BSI), only after fuel nozzle distress, in
accordance with the engine maintenance manual (EMM). The TPE331-10 and -11 series EMM
instructions in Section 72-00-00, Inspection/Check, identify BSI equipment that is not readily
available or effective for this application. Additionally, the EMM does not clearly define nozzle vane
burn-through. This SAIB supplements Honeywell SB TPE331-73-0284 by providing additional
guidance for BSI of the 1st stage turbine nozzle vanes to prevent 1st stage turbine nozzle vane burn-
through and reduce blade failures.
Recommendations
1. The FAA recommends a BSI at every fuel nozzle inspection interval when the fuel nozzle
manifold is removed from the engine, not to exceed 450 hours since last inspection.
2. We also recommend BSI viewing through 4 fuel nozzle boss openings to obtain full
inspection coverage of the 1st stage nozzle.
3. We also recommend using an RF Systems videoscope with a 3.9 mm or 6.9 mm flex insertion
tube or equivalent.
The flex insertion tube must be used with an appropriately sized guide tube as shown in Figure 1
below. When selecting a flex insertion tube, it is important to note that larger diameter tubes allow
more light at the inspection site, but will have less flexibility. Synflex guide tubing provides the
strength and flexibility of aluminum tubing and can be bent by hand. Some borescope suppliers may
provide properly-sized Synflex tubing.
1
Figure 1. Cross-section of TPE331-11U Engine Power Section with Borescope Guide-Tube in
Combustor
Figures 2 – 4 provide photos of TPE331 engine 1st stage turbine stator nozzle vanes with
acceptable and unacceptable conditions.
Area 1: Stator nozzle vane burn-through; unacceptable and unserviceable
Figure 2. 1st Stage Turbine Stator Nozzle with Nozzle Vane Burn-through
2
Area 2: Missing material exposing vane core; acceptable, but re-inspect at next fuel nozzle
inspection interval
Area 3: Blisters, leading or trailing edge cracks, or connecting or near-connecting cracks;
acceptable, but re-inspect at next fuel nozzle inspection interval
Figure 3. 1st Stage Turbine Stator Nozzle with Nozzle Vane Distress
Figure 4. 1st Stage Turbine Stator Nozzle with Acceptable Nozzle Vanes
For Further Information Contact
Joseph Costa, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, 3960
Paramount Blvd., Suite 100, Lakewood, CA 90712; phone: 562-627-5246; fax: 562-627-5210;
email:
[email protected].
For Related Service Information Contact
Honeywell International Inc., 111 S. 34th Street, Phoenix, AZ 85034-2802; phone: 800-601-
3099; Internet: https://myaerospace.honeywell.com/wps/portal.
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Please find attached a Foreign State of Design Advisory document, endorsed by EASA.
This advisory document is also online at https://ad.easa.europa.eu/ad/NE-16-19 .
Should you have any questions, please contact the Agency by e-mail at
[email protected] or by fax,
No.: +49 221 89990 9515.
Safety Information Section Email:
[email protected]
EASA Website
(Attachment is in Acrobat PDF format)
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