The airworthiness of aeronautical products would be in question if the design and quality of the parts are unknown. Positive identification of unapproved parts can be difficult if the parts display characteristics similar to those of an “approved part”. The following guidelines offer a means by which “approved parts” (and their sources) may be assessed.

a. Procurement process. A procedure to ensure the procurement of “approved” parts should be established prior to purchasing parts and material for installation in TC products. This procedure should include the following as a minimum:

  1. Methods of identifying distributors and/or suppliers who have a documentation system, and receiving inspection system which ensures the traceability of their parts to an FAA-approved source.
  2. Methods of screening unfamiliar distributors and/or suppliers to determine if the parts present a potential risk of being “unapproved”. The following are situations which may raise questions:

    (a) A quoted or advertised price which is significantly lower than the price quoted by other distributors and/or suppliers of the same part. (b) A delivery schedule which is significantly shorter than that of other distributors and/or suppliers (when the stock of a like item is exhausted). (c) Sales quotes or discussions from unidentified distributors which create the perception that an unlimited supply of parts, components, or material are available to the end user. (d) A distributor and/or supplier’s inability to provide substantiating documentation that the part was produced pursuant to an FAA approval; or inspected, repaired, overhauled, preserved or altered in accordance with the CFR.

b. Acceptance procedures. Procedures should include a means of identifying SUP during the receiving inspection and prevent their acceptance. Suggested areas to be addressed include the following:

  1. Confirm the packaging of the part identifies the supplier or distributor, and is free from alteration or damage.
  2. Verify that the actual part and delivery receipt reflect the same information as the purchase order regarding part number, serial number, and historical information (if applicable).
  3. Verify that the identification on the part has not been tampered with (e.g., serial number stamped over, label or part/serial numbers improper or missing, vibro-etch or serial numbers located at other than the normal location).
  4. Ensure that the shelf life and/or life limit has not expired, if applicable.
  5. Conduct a visual inspection of the part and supporting documents to the extent necessary to determine if the part is traceable to an FAA-approved source. For detailed guidelines on the identification of replacement parts, refer to AC 20-62. The following are examples of positive forms of identification. (a) FAA Form 8130-3, Airworthiness Approval Tag. (b) Joint Aviation Authorities (JAA) Form One. (c) Maintenance records or release document with approval for return to service. (d) FAA TSO markings. (e) FAA PMA markings. (f) Shipping ticket / invoice from PAH. (g) Direct ship authority letter from PAH.
  6. Evaluate any visible irregularities (e.g., altered or unusual surface, absence of required plating, evidence of prior usage, scratches, new paint over old, attempted exterior repair, pitting or corrosion).
  7. Conduct random sampling of standard hardware packaged in large quantities in a manner which corresponds to the type and quantity of the parts.
  8. Segregate parts of questionable nature and attempt to resolve issues regarding questionable status of part (e.g., obtain necessary documentation if inadvertently not provided, or determine if irregularities are a result of shipping damage and handle accordingly).

c. Supplier Evaluations. Part 21 requires the quality control system of a PAH to provide a means of determining that supplier-produced components (e.g., materials, parts, and subassemblies) or services (e.g., processes, calibration, etc.), conform to FAA-approved design data, and are in a condition for safe operation. Detailed information and guidance on this subject can be found in AC 21-20, Supplier Surveillance Procedures.

Receiving inspection for counterfeit parts detection:

Visual Inspection:

X-ray Fluorescence:

Performed to verify the presence or absence of lead or other materials

X-ray is effective to look for manufacturing differences in die size, lead frame, bond wire patterns and voids. In some cases there have been no bond wires.

Using X-ray, die size, lead frame construction, wire bond gauge and routing can be compared:

X-ray image of dummy part with no die inside and no wires and outside packaging made to appear authentic on the right:

Fein-focus (Real Time) X-ray: It enables inspector to turn part in real time to distinguish perspectives of features. It also displays image on screen instead of film:


Scanning Acousic Microscopy works by direcing focused sound from a transducer at a small point on a target object. Sound hitting the object is either scattered, absorbed, reflected (scattered at 180°) or transmitted (scattered at 180°). It is possible to detect the scattered pulses travelling in a particular direction. A detected pulse informs of the presence of a boundary or object. The Scanning Acoustic Microscope useful in detecting voids, cracks, and delaminations within microelectronic packages.


After performing the nondestructive tests the part should be opened to verify the die. This does not guarantee all of the parts in the lot are the same, but it is a useful tool and is much cheaper than electrical testing.


Curve trace

There are limitations to in-depth physical analysis:

Therefore some electrical analysis is helpful in determining authenticity. Although full datasheet testing is recommended for high reliability applications, a curve trace on each lead is a very effective way to begin an electrical examination of the parts. A "known good" component is required.

Marking Permanency Test

Inspection for re-marking or re-surfacing:

Standard "resistance to solvents" test methods can be effective, but more aggressive methods may be necessary to remove coatings applied to disguise sanding marks, and to reveal other indications that the original device marking has been removed. If part has been re-marked, a grayish to black substance might come off:

Process for the solvents test (Device marking test/device surface test): Examine the sample under a microscope and look for any anomalies affiliated with a counterfeit part such as overall surface texture, excess paint, misaligned text, date code/lot code issues, etc.

Then perform the solvents test.

Device Marking Test:

Immerse the first cotton swab into the three part mineral spirit/one part alcohol mixture and scrub a portion of the first part in a back and forth manner using normal hand pressure over the part markings.

Device Surface Test:

Immerse a second cotton swab in to the acetone solution and on a second part stroke a portion of the part surface away from the part markings five times in a forward direction (as referenced in the IDEA-­STD-­1010 Manual).

If there is enough suspicion, scrape a layer of topping with a razor blade to try and expose an underlying part marking. The next part exhibits uniform texture, indent is rough.

After surface and mold cavity were chemically cleaned, sanding marks became obvious.

Non-uniformity in the surface finish due to the blacktopping removal using acetone.

Electrical testing

After performing all of the inexpensive tests, if there is any uncertainty, a full specification/data sheet electrical test will provide higher confidence in the suspect parts.

Full data sheet testing can be expensive, but if the product is being utilized in a high reliability application, it is highly recommended.

There are also:

Thermal Cycle Testing: 125°C to -55°C at least 20 times (MIL-STD-833 Method 1010 Condition B). Test is done electrically and/or inspected visually.

Burn-In Testing: Precipitates defects by exposing parts to accelerated stress levels (e.g., temperature and voltage)

Effectiveness of the testing methods

According to Dr. Mohammad Tehranipoor from University of Connecticut, there are no metrics to evaluate the effectiveness of counterfeit detection methods. Test results vary from one test lab to another (G-19A round robin test). There are overlaps between test techniques. Decision of a part being counterfeit or not, is done by the subject matter experts based on their level of expertise. It is not clear when a test is sufficient and how the results are quantified. He suggests a need for development of metrics to make data driven decisions (Mohammad Tehranipoor, Counterfeit Parts Detection: Taxonomies and Assessment, NASA QLF, 2013, Cape Canaveral FL).

Taxonomy of detection methods

According to Mohammad Tehranipoor taxonomies of detection methods (Counterfeit Parts Detection: Taxonomies and Assessment, NASA QLF, 2013, Cape Canaveral FL):

Levels of testing

SAE AS5553 Standard for "Fraudulent/Counterfeit Electronic Parts; Avoidance, Detection, Mitigation, and Disposition" summarizes different levels of testing for counterfeit parts:

More examples on visual inspection to detect counterfeit parts:

Manufacturers use:

  • Data codes to identify the date of production (sealing) of a part
  • Lot codes to identify the production the production lot of a part MIL-PRF-38535 paragraph 3.6.6 specifies how date codes must be marked.

Example: Magic part. Data code indicates that the part made in November of 2003 (47th week of 2003), but part received on June 3, 2003. This part was marked with a date code with five months into the future compared to the date of receipt!

These parts had the same manufacturer name, same part number, same date code but three different body molds:

Identical parts on top surface, but indents have completely different markings in bottam surface. First part has two letters and second part has a symbol. In third part, it is unclear it is letter or a symbol:

In another example, the indents to the lower left look similar but middle right indent is not apparent on the bottom part. Counterfeiters sand down the parts to remove original markings. They resurface parts with a process called "blacktopping": Grayish to black substance, this often fills indents (which not to be filled):

Part on the right has indications of remarking because texture of the body is different than indents.

Remarking is indicated by different textures on top side vs. bottom side:

Remarking is indicated by different textrures on top side vs. bottom side. "Blacktopped" surface is a term associated with resurfacing of a component so that it can be remarked:

The below part shows over-sanding:

Shiny, smooth, but orange peel type finish was not natural looking. Scraping the thick looking blacktop exposed the Altera logo under Cypress marking:

Pry marks indicate prior use of part. Chips or cracks on a part is a defect condition:

Damaged leads, scorched body:

Initial bottom markings:

The bottom left image shows an authentic part which is properly marked, similar vintage and configuration as the fake part. The image on the right has a counterfeit logo with incorrect fonts and format (also wrong ink):

The next figures show the bottom marking in black validate configuration, serial number and date:

The part in the next image has laser burn marks. It is belonged to a batch that had markings in a slightly different location on each part. Markings missed the part on the left hand side:

More on markings:

The indent of the part below has an indent which is fille dwith "blacktopping" material which is filled to the edge on one side:

Indents are never partially made, and they are uniform in depth throughout the circle. Original indents are always clean. Here an example of an indent has been filled in with blacktopping material:

In the following example, part on the right is marked "Malaysia", but part on the left is marked "Philippines". They are difficult to see because of blacktopping:

Indents are typically smooth and writing within them should not be textured. Indent is half-filed with blacktopping material. Letters with texture on them are most likely blacktopped:

The above are the new leads - very uniform, consistent finish, exact shape; where as the bottom are used leads - rougher texture and not visible to naked eye.

Normal tooling marks from lead formation operation:

Normal tooling marks from lead formation operation, tinned:

On the other hand, the part on the right has bent, deformed and re-thinned leads:

The next image shows solder and debris on leads with some damaged leads: