Root Cause Analysis (RCA) is not part of TRIZ and no TRIZ procedure requires searching for causes of contradictions or unwanted effects. Moreover, RCA is not adapted to searching for causes of contradictions because it is unaware of this TRIZ concept. It is only purported for searching for causes of unwanted effects. But this drawback can be easily eliminated and RCA can be then applied to searching for causes of contradictions.
One of the TRIZ tools which needs RCA badly is contradiction matrix. Consider the following fresh example.
After real contradictory parameters are mapped into the "classical" ones, the next step in resolving contradictions between them is to apply principles suggested by the matrix for the "classical" parameters. These principles are "local quality" (3), "feedback" (23), "parameter change" (35), "composite materials" (40) for the first pair and "segmentation" (1), "pneumatics & hydraulics" (29), "parameter change" (35), "strong oxidants" (38) for the second.
Now tell me where and what a local quality has to be introduced in order to solve the problem ? What a feedback established ? What a parameter changed ? Which composite materials used and where ? What should be segmented and how ? What pneumatics and hydraulics changed or introduced ? And what strong oxidants to apply and where ?
Contradiction matrix does not answer these questions and no one in his right mind would adopt such an approach to problem solving. Any sensible person would first try and find the causes of contradiction. And only then apply 40 principles (should there still be a need in them after the causes are identified).
Any sensible man would first try to figure out why fuel efficiency precludes the engine from being more resilient to impacts with birds. And only after that he would try to eliminate the root cause. In most cases this would not require 40 principles at all. Simple logic (and negation of the cause's preconditions) would work just fine. But if 40 principles are still required it would be clearer where and how to apply them.
Use of RCA to uncover the root cause of contradiction after it is formulated is a must step before attempting to resolve it with the help of contradiction matrix.