diff --git a/src/ceasiompy/utils/cpacs_preprocessing.py b/src/ceasiompy/utils/cpacs_preprocessing.py
new file mode 100644
index 000000000..3c264a56e
--- /dev/null
+++ b/src/ceasiompy/utils/cpacs_preprocessing.py
@@ -0,0 +1,276 @@
+from pathlib import Path
+import xml.etree.ElementTree as ET
+import math
+
+from cpacspy.cpacspy import CPACS
+
+def _strip_ns(tag: str) -> str:
+    """Strip XML namespace from a tag name."""
+    return tag.split("}", 1)[-1] if "}" in tag else tag
+
+
+def _find_child(parent: ET.Element, name: str):
+    """Find direct child by local (namespace-free) tag name."""
+    for child in parent:
+        if _strip_ns(child.tag) == name:
+            return child
+    return None
+
+
+def _find_path(root: ET.Element, parts: list[str]):
+    """Follow a direct-child path, e.g. ['vehicles', 'profiles', 'wingAirfoils']."""
+    cur = root
+    for p in parts:
+        cur = _find_child(cur, p)
+        if cur is None:
+            return None
+    return cur
+
+
+def _parse_vector(text: str | None) -> list[float]:
+    """Parse CPACS mapType='vector' text into list[float]."""
+    if not text:
+        return []
+    out = []
+    for t in text.replace("\n", "").split(";"):
+        t = t.strip()
+        if t:
+            out.append(float(t))
+    return out
+
+
+def _to_vector(values: list[float]) -> str:
+    """Convert list[float] back to CPACS vector string format."""
+    return ";".join(f"{v:.8g}" for v in values) + ";"
+
+
+def _interp_at_x(x0, y0, z0, x1, y1, z1, x_target):
+    if math.isclose(x1, x0, rel_tol=0.0, abs_tol=1e-15):
+        return x_target, y0, z0
+    t = (x_target - x0) / (x1 - x0)
+    return x_target, y0 + t * (y1 - y0), z0 + t * (z1 - z0)
+
+
+def _clip_lower_te_to_le(x_vals, y_vals, z_vals, x_cut):
+    # Lower branch follows CPACS order TE -> LE.
+    # Remove aft part (x > x_cut), then add one interpolated cut point at x_cut.
+    i_in = next((i for i, x in enumerate(x_vals) if x <= x_cut), None)
+    if i_in is None:
+        return [x_cut], [y_vals[-1]], [z_vals[-1]]
+    if i_in == 0:
+        return x_vals[:], y_vals[:], z_vals[:]
+
+    xi, yi, zi = _interp_at_x(
+        x_vals[i_in - 1],
+        y_vals[i_in - 1],
+        z_vals[i_in - 1],
+        x_vals[i_in],
+        y_vals[i_in],
+        z_vals[i_in],
+        x_cut,
+    )
+    return [xi] + x_vals[i_in:], [yi] + y_vals[i_in:], [zi] + z_vals[i_in:]
+
+
+def _clip_upper_le_to_te(x_vals, y_vals, z_vals, x_cut):
+    # Upper branch follows CPACS order LE -> TE.
+    # Remove aft part (x > x_cut), then add one interpolated cut point at x_cut.
+    i_out = next((i for i, x in enumerate(x_vals) if x > x_cut), None)
+    if i_out is None:
+        return x_vals[:], y_vals[:], z_vals[:]
+    if i_out == 0:
+        return [x_cut], [y_vals[0]], [z_vals[0]]
+
+    xi, yi, zi = _interp_at_x(
+        x_vals[i_out - 1],
+        y_vals[i_out - 1],
+        z_vals[i_out - 1],
+        x_vals[i_out],
+        y_vals[i_out],
+        z_vals[i_out],
+        x_cut,
+    )
+    return x_vals[:i_out] + [xi], y_vals[:i_out] + [yi], z_vals[:i_out] + [zi]
+
+
+def cut_trailing_edge_airfoils(airfoils, te_cut):
+    """
+    Cut trailing edge at x_cut = x_te - te_cut for each airfoil and rebuild
+    each profile as:
+    TE -> lower side -> LE -> upper side -> TE.
+
+    Keep distinct lower/upper TE cut points and close the polyline by
+    repeating TE-lower at the end.
+    Coordinates are then renormalized so x_cut -> 1 for each profile.
+    """
+    tol = 1e-12
+
+    def clip_lower(points, x_cut):
+        """Clip lower branch ordered TE->LE to x <= x_cut."""
+        i_in = next((i for i, (xp, _, _) in enumerate(points) if xp <= x_cut), None)
+        if i_in is None:
+            _, yp, zp = points[-1]
+            return [(x_cut, yp, zp)]
+        if i_in == 0:
+            return points[:]
+        cut = _interp_at_x(*points[i_in - 1], *points[i_in], x_cut)
+        return [cut] + points[i_in:]
+
+    def clip_upper(points, x_cut):
+        """Clip upper branch ordered LE->TE to x <= x_cut."""
+        i_out = next((i for i, (xp, _, _) in enumerate(points) if xp > x_cut), None)
+        if i_out is None:
+            return points[:]
+        if i_out == 0:
+            _, yp, zp = points[0]
+            return [(x_cut, yp, zp)]
+        cut = _interp_at_x(*points[i_out - 1], *points[i_out], x_cut)
+        return points[:i_out] + [cut]
+
+    out = []
+    for airfoil in airfoils:
+        points = list(zip(airfoil["x"], airfoil["y"], airfoil["z"]))
+        if len(points) < 2:
+            out.append(dict(airfoil))
+            continue
+
+        x_te = points[0][0]
+        x_cut = x_te - te_cut
+        if x_cut <= 0.0:
+            raise ValueError(
+                f"Invalid te_cut={te_cut} for airfoil {airfoil.get('uid')}: "
+                f"x_te={x_te}, x_cut={x_cut}."
+            )
+
+        i_le = min(range(len(points)), key=lambda i: points[i][0])
+        lower = clip_lower(points[: i_le + 1], x_cut)   # TE -> LE
+        upper = clip_upper(points[i_le:], x_cut)        # LE -> TE
+
+        same_le = (
+            math.isclose(lower[-1][0], upper[0][0], rel_tol=0.0, abs_tol=tol)
+            and math.isclose(lower[-1][1], upper[0][1], rel_tol=0.0, abs_tol=tol)
+            and math.isclose(lower[-1][2], upper[0][2], rel_tol=0.0, abs_tol=tol)
+        )
+        merged = lower + (upper[1:] if same_le else upper)
+
+        # Close polyline at the trailing edge:
+        # ... -> TE_upper -> TE_lower
+        te_lower = lower[0]
+        merged.append(te_lower)
+
+        scale = 1.0
+        new_x = [xp * scale for xp, _, _ in merged]
+        new_y = [yp * scale for _, yp, _ in merged]
+        new_z = [zp * scale for _, _, zp in merged]
+        import matplotlib.pyplot as plt
+        plt.figure()
+        for i in range(len(new_x) - 1):
+            plt.plot(new_x[i : i + 2], new_z[i : i + 2], "-k", linewidth=1.0)
+        plt.plot(new_x[0], new_z[0], "go", markersize=6, label="start")
+        plt.plot(new_x[-1], new_z[-1], "ro", markersize=6, label="end")
+        plt.title(f"Airfoil {airfoil.get('uid')} after TE cut")
+        plt.xlabel('x-coordinate')
+        plt.ylabel('z-coordinate')
+        plt.grid()
+        plt.axis('equal')
+        plt.legend()
+        plt.show()
+        
+        new_airfoil = dict(airfoil)
+        new_airfoil["x"] = new_x
+        new_airfoil["y"] = new_y
+        new_airfoil["z"] = new_z
+        new_airfoil["points"] = list(zip(new_x, new_y, new_z))
+        out.append(new_airfoil)
+
+    return out
+
+
+def load_wing_airfoils(root: ET.Element):
+    """Load wing airfoils from CPACS profile section into Python dictionaries."""
+    airfoils_node = _find_path(root, ["vehicles", "profiles", "wingAirfoils"])
+    if airfoils_node is None:
+        return []
+
+    data = []
+    for wa in airfoils_node:
+        if _strip_ns(wa.tag) != "wingAirfoil":
+            continue
+
+        uid = wa.attrib.get("uID")
+        point_list = _find_child(wa, "pointList")
+        if point_list is None:
+            continue
+
+        x_node = _find_child(point_list, "x")
+        y_node = _find_child(point_list, "y")
+        z_node = _find_child(point_list, "z")
+        if x_node is None or y_node is None or z_node is None:
+            continue
+
+        x = _parse_vector(x_node.text)
+        y = _parse_vector(y_node.text)
+        z = _parse_vector(z_node.text)
+
+        data.append(
+            {
+                "uid": uid,
+                "x": x,
+                "y": y,
+                "z": z,
+                "points": list(zip(x, y, z)),
+                "x_node": x_node,
+                "y_node": y_node,
+                "z_node": z_node,
+            }
+        )
+    return data
+
+
+def write_airfoils_to_cpacs(tree: ET.ElementTree, airfoils_cut, cpacs_out: Path):
+    """
+    Update <pointList>/<x,y,z> in the XML tree and save a new CPACS file.
+    Matching is done by wingAirfoil uID.
+    """
+    root = tree.getroot()
+    airfoils_now = load_wing_airfoils(root)
+    by_uid = {af["uid"]: af for af in airfoils_cut}
+    updated = 0
+    for af in airfoils_now:
+        uid = af["uid"]
+        if uid not in by_uid:
+            continue
+        new_airfoil = by_uid[uid]
+        af["x_node"].text = _to_vector(new_airfoil["x"])
+        af["y_node"].text = _to_vector(new_airfoil["y"])
+        af["z_node"].text = _to_vector(new_airfoil["z"])
+        updated += 1
+
+    tree.write(cpacs_out, encoding="utf-8", xml_declaration=True)
+    return updated
+
+
+def truncate_trailing_edge(cpacs: CPACS, te_cut: float = 0.4) -> CPACS:
+    tree = ET.parse(cpacs)
+    root = tree.getroot()
+
+    # import the airfoils
+    airfoils = load_wing_airfoils(root)
+    print(f"Loaded {len(airfoils)} airfoils")
+
+    # te_cut -> fraction of chord removed at TE (x_cut = 1 - te_cut)
+    airfoils_cut = cut_trailing_edge_airfoils(airfoils, te_cut)
+
+    
+
+    
+    # save as a new CPACS
+    cpacs_out = cpacs.with_name(f"{cpacs.stem}_tecut_straight_New.xml")
+    n_updated = write_airfoils_to_cpacs(tree, airfoils_cut, cpacs_out)
+    print(f"Updated {n_updated} airfoils in CPACS")
+    print(f"Saved new CPACS: {cpacs_out}")
+    return cpacs_out
+
+
+if __name__ == "__main__":
+    truncate_trailing_edge(Path(__file__).with_name("00_ToolInput(1).xml"))